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Configuration Example - Fence Devices

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Red Hat Enterprise Linux 5

Configuring Fence Devices in a Red Hat Cluster

Edition 2

Legal Notice

Abstract

This book describes a procedure for configuring fence devices in a Red Hat Cluster using Conga.

Chapter 1. Introduction

1.1. About This Guide

This book describes procedures for configuring fence devices in a Red Hat Cluster using Conga.

1.2. Audience

This book is intended to be used by system administrators managing systems running the Linux operating system. It requires familiarity with Red Hat Enterprise Linux 5 and Red Hat Cluster Suite.

1.3. Software Versions

Table 1.1. Software Versions
Software	Description
RHEL5	refers to Red Hat Enterprise Linux 5 and higher
GFS	refers to GFS for Red Hat Enterprise Linux 5 and higher

1.4. Related Documentation

For more information about using Red Hat Enterprise Linux, refer to the following resources:

Red Hat Enterprise Linux Installation Guide — Provides information regarding installation of Red Hat Enterprise Linux 5.
Red Hat Enterprise Linux Deployment Guide — Provides information regarding the deployment, configuration and administration of Red Hat Enterprise Linux 5.

For more information about Red Hat Cluster Suite for Red Hat Enterprise Linux 5, refer to the following resources:

Red Hat Cluster Suite Overview — Provides a high level overview of the Red Hat Cluster Suite.
Configuring and Managing a Red Hat Cluster — Provides information about installing, configuring and managing Red Hat Cluster components.
Logical Volume Manager Administration — Provides a description of the Logical Volume Manager (LVM), including information on running LVM in a clustered environment.
Global File System: Configuration and Administration — Provides information about installing, configuring, and maintaining Red Hat GFS (Red Hat Global File System).
Global File System 2: Configuration and Administration — Provides information about installing, configuring, and maintaining Red Hat GFS2 (Red Hat Global File System 2).
Using Device-Mapper Multipath — Provides information about using the Device-Mapper Multipath feature of Red Hat Enterprise Linux 5.
Using GNBD with Global File System — Provides an overview on using Global Network Block Device (GNBD) with Red Hat GFS.
Linux Virtual Server Administration — Provides information on configuring high-performance systems and services with the Linux Virtual Server (LVS).
Red Hat Cluster Suite Release Notes — Provides information about the current release of Red Hat Cluster Suite.

Red Hat Cluster Suite documentation and other Red Hat documents are available in HTML, PDF, and RPM versions on the Red Hat Enterprise Linux Documentation CD and online at http://www.redhat.com/docs/.

Chapter 2. Configuring Fence Devices in a Red Hat Cluster

This document provides configuration examples that show the steps needed to configure fence devices in a Red Hat cluster using the Conga configuration tool. For general information about fencing and fence device configuration, see Configuring and Managing a Red Hat Cluster.

This remainder of this document is organized as follows:

Chapter 3, Configuring an APC Switch as a Fence Device describes the procedure for configuring an APC switch as a fence device in a Red Hat cluster.
Chapter 4, Configuring IPMI Management Boards as Fencing Devices describes the procedure for configuring IPMI management boards as fence devices in a Red Hat cluster.
Chapter 5, Configuring HP ILO Management Boards as Fencing Devices describes the procedure for configuring HP iLO management boards as fence devices in a Red Hat cluster.
Chapter 6, Configuring Fencing with Dual Power Supplies describes the procedure for configuring two APC switches using separate power supplies to fence each cluster node in a Red Hat cluster.
Chapter 7, Configuring a Backup Fencing Method describes the procedure for configuring two APC switches using separate power supplies as a main fencing method and a separate IPMI management board as a backup fencing method to fence each cluster node in a Red Hat cluster.
Chapter 8, Configuring Fencing using SCSI Persistent Reservations describes the procedure for configuring fencing on a system using SCSI persistent reservations in a Red Hat cluster.
Chapter 9, Troubleshooting provides some guidelines to follow when your configuration does not behave as expected.
Chapter 10, The GFS Withdraw Function summarizes some general concerns to consider when configuring fence devices in a Red Hat cluster.

Chapter 3. Configuring an APC Switch as a Fence Device

This chapter provides the procedures for configuring an APC switch as a fence device in a Red Hat cluster using the Conga configuration tool.

Figure 3.1, “Using an APC Switch as a Fence Device” shows the configuration this procedure yields. In this configuration a three node cluster uses an APC switch as the fencing device. Each node in the cluster is connected to a port in the APC switch.

Figure 3.1. Using an APC Switch as a Fence Device

3.1. APC Fence Device Prerequisite Configuration

Table 3.1, “Configuration Prerequisities” summarizes the prerequisite components that have been set up before this procedure begins.

Table 3.1. Configuration Prerequisities
Component	Name	Comment
cluster	apcclust	three-node cluster
cluster node	clusternode1.example.com	node in cluster apcclust configured with APC switch to administer power supply
cluster node	clusternode2.example.com	node in cluster apcclust configured with APC switch to administer power supply
cluster node	clusternode3.example.com	node in cluster apcclust configured with APC switch to administer power supply
IP address	10.15.86.96	IP address for the APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
login	apclogin	login value for the APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	apcpword	password for the APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
port	1	port number on APC switch that clusternode1.example.com connects to
port	2	port number on APC switch that clusternode2.example.com connects to
port	3	port number on APC switch that clusternode3.example.com connects to

3.2. APC Fence Device Components to Configure

This procedure configures an APC switch as a fence device that will be used for each node in cluster apcclust. Then the procedure configures that switch as the fencing device for clusternode1.example.com, clusternode2.example.com, and clusternode1.example.com.

Table 3.2, “Fence Device Components to Configure for APC Fence Device” summarizes the components of the APC fence device that this procedure configures for each of the cluster nodes in clusternode1.example.com.

Table 3.2. Fence Device Components to Configure for APC Fence Device
Fence Device Component	Value	Description
Fencing Type	APC Power Switch	type of fencing device to configure
Name	apcfence	name of the APC fencing device
IP address	10.15.86.96	IP address of the APC switch to configure as a fence device for node1.example.com, node2.example.com, and node3.example.com
login	apclogin	login value for the APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	apcpword	password for the APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com

Table 3.3, “Fence Agent Components to Specify for Each Node in apcclust ” summarizes the components of the APC fence device that you must specify for the cluster nodes in apcclust.

Table 3.3. Fence Agent Components to Specify for Each Node in apcclust
Fence Agent Component	Value	Description
fence device	apcfence	name of the APC fence device you defined as a shared device
port	1	port number on the APC switch for node1.example.com
port	2	port number on the APC switch for node2.example.com
port	3	port number on the APC switch for node3.example.com

The remainder of the fence device components that you configure for each node appear automatically when you specify that you will be configuring the apcfence fence device that you previously defined as a shared fence device.

3.3. APC Fence Device Configuration Procedure

This section provides the procedure for adding an APC fence device to each node of cluster apcclust. This example uses the same APC switch for each cluster node. The APC fence device will first be configured as a shared fence device. After configuring the APC switch as a shared fence device, the device will be added as a fence device for each node in the cluster.

To configure an APC switch as a shared fence device using Conga, perform the following procedure:

As an administrator of luci Select the cluster tab. This displays the Choose a cluster to administer screen.
From the Choose a cluster to administer screen, you should see the previously configured cluster apcclust displayed, along with the nodes that make up the cluster. Click on apcclust to select the cluster.
At the detailed menu for the cluster apcclust (below the clusters menu on the left side of the screen), click Shared Fence Devices. Clicking Shared Fence Devices causes the display of any shared fence devices previously configured for a cluster and causes the display of menu items for fence device configuration: Add a Fence Device and Configure a Fence Device.
Click Add a Fence Device. Clicking Add a Fence Device causes the Add a Sharable Fence Device page to be displayed.
At the Add a Sharable Fence Device page, click the drop-down box under Fencing Type and select APC Power Switch. This causes Conga to display the components of an APC Power Switch fencing type, as shown in Figure 3.2, “Adding a Sharable Fence Device”.
Figure 3.2. Adding a Sharable Fence Device
For Name, enter apcfence.
For IP Address, enter 10.15.86.96.
For Login, enter apclogin.
For Password, enter apcpword.
For Password Script, leave blank.
Click Add this shared fence device.
Clicking Add this shared fence device causes a progress page to be displayed temporarily. After the fence device has been added, the detailed cluster properties menu is updated with the fence device under Configure a Fence Device.

After configuring the APC switch as a shared fence device, use the following procedure to configure the APC switch as the fence device for node clusternode1.example.com

At the detailed menu for the cluster apcclust (below the clusters menu), click Nodes. Clicking Nodes causes the display of the status of each node in apcclust.
At the bottom of the display for node clusternode1.example.com, click Manage Fencing for this Node. This displays the configuration screen for node clusternode1.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown menu to display.
From the dropdown menu, the apcfence fence device you have already created should display as one of the menu options under Use an Existing Fence Device. Select apcfence (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login, Password, and Password Script values already configured, as defined when you configured apcfence as a shared fence device. This is shown in Figure 3.3, “Adding an Existing Fence Device to a Node”.
Figure 3.3. Adding an Existing Fence Device to a Node
For Port, enter 1. Do not enter any value for Switch.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, Click OK. A progress page is displayed after which the display returns to the status page for clusternode1.example.com in cluster apcclust.

After configuring apcfence as the fencing device for clusternode1.example.com, use the same procedure to configure apcfence as the fencing device for clusternode2.example.com, specifying Port 2 for clusternode2.example.com, as in the following procedure:

On the status page for clusternode1.example.com in cluster apcclust, the other nodes in apcclust are displayed below the Configure menu item below the Nodes menu item on the left side of the screen. Click clusternode2.example.com to display the status screen for clusternode2.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
As for clusternode1.example.com, the apcfence fence device should display as one of the menu options on the dropdown menu, under Use an Existing Fence Device. Select apcfence (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login, Password, Password Script values already configured, as defined when you configured apcfence as a shared fence device.
For Port, enter 2. Do not enter any value for Switch.
Click Update main fence properties.

Similarly, configure apcfence as the main fencing method for clusternode3.example.com, specifying 3 as the Port number.

3.4. Cluster Configuration File with APC Fence Device

Configuring a cluster with Conga modifies the cluster configuration file. This section shows the cluster configuration file before and after the procedures documented in Section 3.3, “APC Fence Device Configuration Procedure” were performed.

Before the cluster resources and service were configured, the cluster.conf file appeared as follows.


<?xml version="1.0"?>
<cluster alias="apcclust" config_version="12" name="apcclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices/>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

After the cluster resources and service were configured, the cluster.conf file appears as follows.


<?xml version="1.0"?>
<cluster alias="apcclust" config_version="19" name="apcclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="apcfence" port="1"/>
                                </method>
                        </fence>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="apcfence" port="2"/>
                                </method>
                        </fence>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="apcfence" port="3"/>
                                </method>
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices>
                <fencedevice agent="fence_apc" ipaddr="10.15.86.96" login="apclogin" name="apcfence" passwd="apcpword"/>
        </fencedevices>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

3.5. Testing the APC Fence Device Configuration

To check whether the configuration you have defined works as expected, you can use the fence_node to fence a node manually. The fence_node program reads the fencing settings from the cluster.conf file for the given node and then runs the configured fencing agent against the node.

To test whether the APC switch has been successfully configured as a fence device for the three nodes in cluster apcclust, execute the following commands and check whether the nodes have been fenced.

# /sbin/fence_node clusternode1.example.com
# /sbin/fence_node clusternode2.example.com
# /sbin/fence_node clusternode3.example.com

Chapter 4. Configuring IPMI Management Boards as Fencing Devices

This chapter provides the procedures for configuring IPMI management boards as fencing devices in a Red Hat cluster using the Conga configuration tool.

Figure 4.1, “Using IPMI Management Boards as Fence Devices” shows the configuration this procedure yields. In this configuration each node of a three node cluster uses an IPMI management board as its fencing device.

Note

Note that in this configuration each system has redundant power and is hooked into two independent power sources. This ensures that the management board would still function as needed in a cluster even if you lose power from one of the sources.

Figure 4.1. Using IPMI Management Boards as Fence Devices

4.1. IPMI Fence Device Prerequisite Configuration

Table 4.1, “Configuration Prerequisities” summarizes the prequisite components that have been set up before this procedure begins.

Table 4.1. Configuration Prerequisities
Component	Name	Comment
cluster	ipmiclust	three-node cluster
cluster node	clusternode1.example.com	node in cluster ipmiclust configured with IPMI management board and two power supplies
IP address	10.15.86.96	IP address for IPMI management board for clusternode1.example.com
login	ipmilogin	login name for IPMI management board for clusternode1.example.com
password	ipmipword	password IPMI management board for clusternode1.example.com
cluster node	clusternode2.example.com	node in cluster ipmiclust configured with IPMI management board and two power supplies
IP address	10.15.86.97	IP address for IPMI management board for clusternode2.example.com
login	ipmilogin	login name for IPMI management board for clusternode2.example.com
password	ipmipword	password for IPMI management board for clusternode2.example.com
cluster node	clusternode3.example.com	node in cluster ipmiclust configured with IPMI management board and two power supplies
IP address	10.15.86.98	IP address for IPMI management board for clusternode3.example.com
login	ipmilogin	login name for IPMI management board for clusternode3.example.com
password	ipmipword	password for IPMI management board for clusternode3.example.com

4.2. IPMI Fence Device Components to Configure

This procedure configures the IPMI management board as a fence device for each node in cluster ipmiclust.

Table 4.2, “Fence Agent Components to Configure for clusternode1.example.com” summarizes the components of the IPMI fence device that this procedure configures for cluster node clusternode1.example.com.

Table 4.2. Fence Agent Components to Configure for clusternode1.example.com
Fence Agent Component	Value	Description
Name	ipmifence1	name of the IPMI fencing device
IP address	10.15.86.96	IP address of the IPMI management board to configure as a fence device for clusternode1.example.com
IPMI login	ipmilogin	login identity for the IPMI management board for clusternode1.example.com
password	ipmipword	password for the IPMI management board for clusternode1.example.com
authentication type	password	authentication type for the IPMI management board for clusternode1.example.com

Table 4.3, “Fence Agent Components to Configure for clusternode2.example.com” summarizes the components of the IPMI fence device that this procedure configures for cluster node clusternode2.example.com.

Table 4.3. Fence Agent Components to Configure for clusternode2.example.com
Fence Agent Component	Value	Description
Name	ipmifence2	name of the IPMI fencing device
IP address	10.15.86.97	IP address of the IPMI management board to configure as a fence device for clusternode2.example.com
IPMI login	ipmilogin	login identity for the IPMI management board for clusternode2.example.com
password	ipmipword	password for the IPMI management board for clusternode2.example.com
authentication type	password	authentication type for the IPMI management board for clusternode2.example.com

Table 4.4, “Fence Agent Components to Configure for clusternode3.example.com” summarizes the components of the IPMI fence device that this procedure configures for cluster node clusternode3.example.com.

Table 4.4. Fence Agent Components to Configure for clusternode3.example.com
Fence Agent Component	Value	Description
Name	ipmifence3	name of the IPMI fencing device
IP address	10.15.86.98	IP address of the IPMI management board to configure as a fence device for clusternode3.example.com
IPMI login	ipmilogin	login identity for the IPMI management board for clusternode3.example.com
password	ipmipword	password for the IPMI management board for clusternode3.example.com
authentication type	password	authentication type for the IPMI management board for clusternode3.example.com

4.3. IPMI Fence Device Configuration Procedure

This section provides the procedure for adding an IPMI fence device to each node of cluster ipmiclust. Each node of ipmiclust is managed by its own IPMI management board.

Use the following procedure to configure the IPMI management board as the fence device for node clusternode1.example.com using Conga:

As an administrator of luci Select the cluster tab. This displays the Choose a cluster to administer screen.
From the Choose a cluster to administer screen, you should see the previously configured cluster ipmiclust displayed, along with the nodes that make up the cluster. Click on clusternode1.example.com. This displays the configuration screen for node clusternode1.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Create a new Fence Device, select IPMI Lan. This displays a fence device configuration menu, as shown in Figure 4.2, “Creating an IPMI Fence Device”.
Figure 4.2. Creating an IPMI Fence Device
For Name, enter ipmifence1.
For IP Address, enter 10.15.86.96.
For Login, enter ipmilogin.
For Password, enter ipmipword.
For Password Script, leave the field blank.
For Authentication type, enterpassword. This field specifies the IPMI authentication type. Possible values for this field are none, password, md2, or md5.
Leave the Use Lanplus field blank. You would check this field if your fence device is a Lanplus-capable interface such as iLO2.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode1.example.com in cluster ipmiclust.

After configuring an IPMI fence device for clusternode1.example.com, use the following procedure to configure an IPMI fence device for clusternode2.example.com.

From the configuration page for clusternode1.example.com, a menu appears on the left of the screen for cluster ipmiclust. Select the node clusternode2.example.com. The configuration page for clusternode2.example.com appears, with no fence device configured.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Create a new Fence Device, select IPMI Lan. This displays a fence device configuration menu.
For Name, enter ipmifence2.
For IP Address, enter 10.15.86.97.
For Login, enter ipmilogin.
For Password, enter ipmipword.
For Password Script, leave the field blank.
For Authentication type, enterpassword. This field specifies the IPMI authentication type. Possible values for this field are none, password, md2, or md5.
Leave the Use Lanplus field blank.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode1.example.com in cluster ipmiclust.

After configuring ipmifence2 as the fencing device for clusternode2.example.com, select node clusternode3.example.com from the menu on the left side of the page and configure an IPMI fence device for that node using the same procedure as you did to configure the fence devices for clusternode2.example.com and clusternode3.example.com. For clusternode3.example.com , use ipmifence3 as the name of the fencing method and 10.15.86.98 as the IP address. Otherwise, use the same values for the fence device parameters.

4.4. Cluster Configuration File with IPMI Fence Device

Configuring a cluster with Conga modifies the cluster configuration file. This section shows the cluster configuration file before and after the procedures documented in Section 4.3, “IPMI Fence Device Configuration Procedure” and were performed.

Before the cluster resources and service were configured, the cluster.conf file appeared as follows.


<?xml version="1.0"?>
<cluster alias="ipmiclust" config_version="12" name="ipmiclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        <fence>
                                <method name="1"/>
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices/>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

After the cluster resources and service were configured, the cluster.conf file appears as follows.


<?xml version="1.0"?>
<cluster alias="ipmiclust" config_version="27" name="ipmiclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="ipmifence1"/>
                                </method>
                        </fence>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="ipmifence2"/>
                                </method>
                        </fence>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="ipmifence3"/>
                                </method>
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices>
                <fencedevice agent="fence_ipmilan" ipaddr="10.15.86.96" login="ipmilogin" name="ipmifence1" passwd="ipmipword" />
                <fencedevice agent="fence_ipmilan" ipaddr="10.15.86.97" login="ipmilogin" name="ipmifence2" passwd="ipmipword" />
                <fencedevice agent="fence_ipmilan" ipaddr="10.15.86.98" login="ipmilogin" name="ipmifence3" passwd="ipmipword" />
        </fencedevices>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

4.5. Testing the IPMI Fence Device Configuration

To test whether the IPMI management boards have been successfully configured as fence devices for the three nodes in cluster ipmiclust, execute the following commands and check whether the nodes have been fenced.

# /sbin/fence_node clusternode1.example.com
# /sbin/fence_node clusternode2.example.com
# /sbin/fence_node clusternode3.example.com

Chapter 5. Configuring HP ILO Management Boards as Fencing Devices

This chapter provides the procedures for configuring HP iLO management boards as fencing devices in a Red Hat cluster using the Conga configuration tool.

Figure 5.1, “Using HP iLO Management Boards as Fence Devices” shows the configuration this procedure yields. In this configuration each node of a three node cluster uses an HP iLO management board as its fencing device.

Note

Figure 5.1. Using HP iLO Management Boards as Fence Devices

5.1. HP iLO Fence Device Prerequisite Configuration

Table 5.1, “Configuration Prerequisities” summarizes the prequisite components that have been set up before this procedure begins.

Table 5.1. Configuration Prerequisities
Component	Name	Comment
cluster	hpiloclust	three-node cluster
cluster node	clusternode1.example.com	node in cluster hpiloclust configured with HP iLO management board and two power supplies
hostname	hpilohost1	host name for HP iLO management board for clusternode1.example.com
login	hpilologin	login name for HP iLO management board for clusternode1.example.com
password	hpilopword	password HP iLO management board for clusternode1.example.com
cluster node	clusternode2.example.com	node in cluster hpiloclust configured with HP iLO management board and two power supplies
hostname	hpilohost2	hostname for HP iLO management board for clusternode2.example.com
login	hpilologin	login name for HP iLO management board for clusternode2.example.com
password	hpilopword	password for HP iLO management board for clusternode2.example.com
cluster node	clusternode3.example.com	node in cluster hpiloclust configured with HP iLO management board and two power supplies
hostname	hpilohost3	host name for HP iLO management board for clusternode3.example.com
login	hpilologin	login name for HP iLO management board for clusternode3.example.com
password	hpilopword	password for HP iLO management board for clusternode3.example.com

5.2. HP iLO Fence Device Components to Configure

This procedure configures the HP iLO management board as a fence device for each node in cluster hpiloclust.

Table 5.2, “Fence Agent Components to Configure for clusternode1.example.com” summarizes the components of the HP iLO fence device that this procedure configures for cluster node clusternode1.example.com.

Table 5.2. Fence Agent Components to Configure for clusternode1.example.com
Fence Agent Component	Value	Description
Name	hpilofence1	name of the HP iLO fencing device
hostname	hpilohost1	host name of the HP iLO management board to configure as a fence device for clusternode1.example.com
HP iLO login	hpilologin	login identity for the HP iLO management board for clusternode1.example.com
password	hpilopword	password for the HP iLO management board for clusternode1.example.com

Table 5.3, “Fence Agent Components to Configure for clusternode2.example.com” summarizes the components of the HP iLO fence device that this procedure configures for cluster node clusternode2.example.com.

Table 5.3. Fence Agent Components to Configure for clusternode2.example.com
Fence Agent Component	Value	Description
Name	hpilofence2	name of the HP iLO fencing device
hostname	hpilohost2	host name of the HP iLO management board to configure as a fence device for clusternode2.example.com
HP iLO login	hpilologin	login identity for the HP iLO management board for clusternode2.example.com
password	hpilopword	password for the HP iLO management board for clusternode2.example.com

Table 5.4, “Fence Agent Components to Configure for clusternode3.example.com” summarizes the components of the HP iLO fence device that this procedure configures for cluster node clusternode3.example.com.

Table 5.4. Fence Agent Components to Configure for clusternode3.example.com
Fence Agent Component	Value	Description
Name	hpilofence3	name of the HP iLO fencing device
hostname	hpilohost3	IP address of the HP iLO management board to configure as a fence device for clusternode3.example.com
HP iLO login	hpilologin	login identity for the HP iLO management board for clusternode3.example.com
password	hpilopword	password for the HP iLO management board for clusternode3.example.com

5.3. HP iLO Fence Device Configuration Procedure

This section provides the procedure for adding an HP iLO fence device to each node of cluster hpiloclust. Each node of hpiloclust is managed by its own HP iLO management board.

Use the following procedure to configure the HP iLO management board as the fence device for node clusternode1.example.com using Conga:

As an administrator of luci Select the cluster tab. This displays the Choose a cluster to administer screen.
From the Choose a cluster to administer screen, you should see the previously configured cluster hpiloclust displayed, along with the nodes that make up the cluster. Click on clusternode1.example.com. This displays the configuration screen for node clusternode1.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Create a new Fence Device, select HP iLO. This displays a fence device configuration menu, as shown in Figure 5.2, “Creating an HP iLO Fence Device”.
Figure 5.2. Creating an HP iLO Fence Device
For Name, enter hpilofence1.
For Hostname, enter hpilohost1.
For Login, enter hpilologin.
For Password, enter hpilopword.
For Password Script, leave the field blank.
For Use SSH, leave the field blank. You would check this box of your system uses SSH to access the HP iLO management board.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode1.example.com in cluster hpiloclust.

After configuring an HP iLO fence device for clusternode1.example.com, use the following procedure to configure an HP iLO fence device for clusternode2.example.com.

From the configuration page for clusternode1.example.com, a menu appears on the left of the screen for cluster hpiloclust. Select the node clusternode2.example.com. The configuration page for clusternode2.example.com appears, with no fence device configured.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Create a new Fence Device, select HP iLO. This displays a fence device configuration menu.
For Name, enter hpilofence2.
For Hostname, enter hpilohost2.
For Login, enter hpilologin.
For Password, enter hpilopword.
For Password Script, leave the field blank.
For Use SSH, leave the field blank.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode1.example.com in cluster hpiloclust.

After configuring hpilofence2 as the fencing device for clusternode2.example.com, select node clusternode3.example.com from the menu on the left side of the page and configure an HP iLO fence device for that node using the same procedure as you did to configure the fence devices for clusternode2.example.com and clusternode3.example.com. For clusternode3.example.com , use hpilofence3 as the name of the fencing method and hpilohost3 as the host name. Otherwise, use the same values for the fence device parameters.

5.4. Cluster Configuration File with HP iLO Fence Device

Configuring a cluster with Conga modifies the cluster configuration file. This section shows the cluster configuration file before and after the procedures documented in Section 5.3, “HP iLO Fence Device Configuration Procedure” and were performed.

Before the cluster resources and service were configured, the cluster.conf file appeared as follows.


<?xml version="1.0"?>
<cluster alias="hpiloclust" config_version="12" name="hpiloclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        <fence>
                                <method name="1"/>
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices/>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

After the cluster resources and service were configured, the cluster.conf file appears as follows.


<?xml version="1.0"?>
<cluster alias="backupclust" config_version="26" name="backupclust">
    <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
    <clusternodes>
        <clusternode name="doc-10.lab.msp.redhat.com" nodeid="1" votes="1">
                <fence>
                        <method name="1">
                                <device name="hpilofence1"/>
                        </method>
                </fence>
        </clusternode>
        <clusternode name="doc-11.lab.msp.redhat.com" nodeid="2" votes="1">
                <fence>
                        <method name="1">
                                <device name="hpilofence2"/>
                        </method>
                </fence>
        </clusternode>
        <clusternode name="doc-12.lab.msp.redhat.com" nodeid="3" votes="1">
                <fence>
                        <method name="1">
                                <device name="hpilofence3"/>
                        </method>
                </fence>
        </clusternode>
    </clusternodes>
    <cman/>
    <fencedevices>
        <fencedevice agent="fence_ilo" hostname="hpilohost1" login="hpilologin" name="hpilofence1" passwd="hpilopword"/>
        <fencedevice agent="fence_ilo" hostname="hpilohost2" login="hpilologin" name="hpilofence2" passwd="hpilologin"/>
        <fencedevice agent="fence_ilo" hostname="hpilohost3" login="hpilologin" name="hpilofence3" passwd="hpilopword"/>
    </fencedevices>
    <rm>
        <failoverdomains/>
        <resources/>
    </rm>
</cluster>

5.5. Testing the HP iLO Fence Device Configuration

To test whether the HP iLO management boards have been successfully configured as fence devices for the three nodes in cluster hpiloclust, execute the following commands and check whether the nodes have been fenced.

# /sbin/fence_node clusternode1.example.com
# /sbin/fence_node clusternode2.example.com
# /sbin/fence_node clusternode3.example.com

Chapter 6. Configuring Fencing with Dual Power Supplies

If your system is configured with redundant power supplies for your system, you must be sure to configure fencing so that your nodes fully shut down when they need to be fenced. If you configure each power supply as a separate fence method, each power supply will be fenced separately; the second power supply will allow the system to continue running when the first power supply is fenced and the system will not be fenced at all. To configure a system with dual power supplies, you must configure your fence devices so that both power supplies are shut off and the system is taken completely down. This requires that you configure two fencing devices inside of a single fencing method.

This chapter provides the procedures for using the Conga configuration tool in a Red Hat cluster to configure fencing with dual power supplies.

Figure 6.1, “Fence Devices with Dual Power Supplies” shows the configuration this procedure yields. In this configuration, there are two APC network power switches, each of which runs on its own separate UPS and has its own unique IP address. Each node in the cluster is connected to a port on each APC switch.

Figure 6.1. Fence Devices with Dual Power Supplies

6.1. Dual Power Fencing Prerequisite Configuration

Table 6.1, “Configuration Prerequisities” summarizes the prerequisite components that have been set up before this procedure begins.

Table 6.1. Configuration Prerequisities
Component	Name	Comment
cluster	apcclust	three-node cluster
cluster node	clusternode1.example.com	node in cluster apcclust configured with 2 APC switches to administer power supply
cluster node	clusternode2.example.com	node in cluster apcclust configured with 2 APC switches to administer power supply
cluster node	clusternode3.example.com	node in cluster apcclust configured with 2 APC switches to administer power supply
IP address	10.15.86.96	IP address for the first APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com. This switch runs on its own UPS.
IP address	10.15.86.97	IP address for the second APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com. This switch runs on its own UPS.

Table 6.2, “Configuration Prerequisities” summarizes the prerequisite components that have been set up for each of the APC switches before this procedure begins.

Table 6.2. Configuration Prerequisities
Component	Name	Comment
login	apclogin	login value for both of the the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	apcpword	password for both the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
port	1	port number on both of the APC switches that clusternode1.example.com connects to
port	2	port number on both of the APC switches that clusternode2.example.com connects to
port	3	port number on both of the APC switches that clusternode3.example.com connects to

6.2. Fence Device Components to Configure

This procedure configures two APC switches as fence devices that will be used for each node in cluster apcclust. Then the procedure configures both of those switches as part of one fencing method for clusternode1.example.com, clusternode2.example.com, and clusternode1.example.com.

Table 6.3, “Fence Device Components to Configure for APC Fence Device” summarizes the components of the APC fence devices that this procedure configures for cluster node clusternode1.example.com.

Table 6.3. Fence Device Components to Configure for APC Fence Device
Fence Device Component	Value	Description
Fencing Type	APC Power Switch	type of fencing device to configure for each APC switch
Name	pwr01	name of the first APC fencing device for node1.example.com, node2.example.com, and node3.example.com
IP address	10.15.86.96	IP address of the first APC switch to configure as a fence device for node1.example.com, node2.example.com, and node3.example.com
Name	pwr02	name of the second APC fencing device for node1.example.com, node2.example.com, and node3.example.com
IP address	10.15.86.97	IP address of the second APC switch to configure as a fence device for node1.example.com, node2.example.com, and node3.example.com
login	apclogin	login value for the each of the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	apcpword	password for each of the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com

Table 6.4, “Fence Agent Components to Specify for Each Node in apcclust ” summarizes the components of each of the APC fence devices that you must specify for the cluster nodes in apcclust.

Table 6.4. Fence Agent Components to Specify for Each Node in apcclust
Fence Agent Component	Value	Description
fence device	pwr01	name of the first APC fence device you defined as a shared device
fence device	pwr02	name of the second APC fence device you defined as a shared device
port	1	port number on each of the APC switches for node1.example.com
port	2	port number on each of the APC switches for node2.example.com
port	3	port number on each of the APC switches for node3.example.com

The remainder of the fence device components that you configure for each fence device for each node appear automatically when you specify that you will be configuring the pwr01 or pwr02 fence device that you previously defined as a shared fence device.

6.3. Dual Power Fencing Configuration Procedure

This section provides the procedure for adding two APC fence devices to each node of cluster apcclust, configured as a single fence method to ensure that the fencing is successful. This example uses the same APC switches for each cluster node. The APC switches will first be configured as shared fence devices. After configuring the APC switches as shared fence devices, the devices will be added as fence device for each node in the cluster.

To configure the first APC switch as a shared fence device named pwr01 using Conga, perform the following procedure:

As an administrator of luci Select the cluster tab. This displays the Choose a cluster to administer screen.
From the Choose a cluster to administer screen, you should see the previously configured cluster apcclust displayed, along with the nodes that make up the cluster. Click on apcclust to select the cluster.
At the detailed menu for the cluster apcclust (below the clusters menu on the left side of the screen), click Shared Fence Devices. Clicking Shared Fence Devices causes the display of any shared fence devices previously configured for a cluster and causes the display of menu items for fence device configuration: Add a Fence Device and Configure a Fence Device.
Click Add a Fence Device. Clicking Add a Fence Device causes the Add a Sharable Fence Device page to be displayed.
At the Add a Sharable Fence Device page, click the drop-down box under Fencing Type and select APC Power Switch. This causes Conga to display the components of an APC Power Switch fencing type, as shown in Figure 6.2, “Adding a Sharable Fence Device”.
Figure 6.2. Adding a Sharable Fence Device
For Name, enter pwr01.
For IP Address, enter 10.15.86.96.
For Login, enter apclogin.
For Password, enter apcpword.
For Password Script, leave blank.
Click Add this shared fence device.
Clicking Add this shared fence device causes a progress page to be displayed temporarily. After the fence device has been added, the detailed cluster properties menu is updated with the fence device under Configure a Fence Device.

To configure the second APC switch as a shared fence device named pwr02, perform the following procedure:

After configuring the first APC switch as shared fence device pwr01, click Add a Fence Device from the detailed menu for the cluster apcclust (below the clusters menu on the left side of the screen). This displays the Add a Sharable Fence Device page.
At the Add a Sharable Fence Device page, click the drop-down box under Fencing Type and select APC Power Switch. This causes Conga to display the components of an APC Power Switch fencing type.
For Name, enter pwr02.
For IP Address, enter 10.15.86.97.
For Login, enter apclogin.
For Password, enter apcpword.
For Password Script, leave blank.
Click Add this shared fence device.
Clicking Add this shared fence device causes a progress page to be displayed temporarily. After the fence device has been added, the detailed cluster properties menu is updated with the fence device under Configure a Fence Device.

After configuring the APC switches as shared fence devices, use the following procedure to configure the first APC switch, pwr01, as the first fence device for node clusternode1.example.com.

At the detailed menu for the cluster apcclust (below the clusters menu), click Nodes. Clicking Nodes causes the display of the status of each node in apcclust.
At the bottom of the display for node clusternode1.example.com, click Manage Fencing for this Node. This displays the configuration screen for node clusternode1.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown menu to display.
From the dropdown menu, the pwr01 and pwr02 fence devices you have already created should display as one of the menu options under Use an Existing Fence Device. Select pwr01 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login,Password, and Password Script values already configured, as defined when you configured pwr01 as a shared fence device. (The Password value does not display, but you may not alter it.) This is shown in Figure 6.3, “Adding Fence Device pwr01 to a Node”.
Figure 6.3. Adding Fence Device pwr01 to a Node
For Port, enter 1. Do not enter any value for Switch.

Before updating the main fence properties for this node, use the following procedure to add pwr02 as the second fence device of the main fencing method for node clusternode1.example.com.

Beneath the configuration information for pwr01 that you have entered, click Add a fence device to this level. This displays the dropdown menu again.
From the dropdown menu, select pwr02 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login,Password, and Password Script values already configured, as defined when you configured pwr02 as a shared fence device. This is shown in Figure 6.4, “Adding Fence Device pwr02 to a Node”.
Figure 6.4. Adding Fence Device pwr02 to a Node
For Port, enter 1. Do not enter any value for Switch.

After entering the configuration information for both power sources to use as fence devices, you can update the main fence properties using the following procedure.

Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, Click OK. A progress page is displayed after which the display returns to the status page for clusternode1.example.com in cluster apcclust.

After configuring pwr01 and pwr02 as the fencing devices for clusternode1.example.com, use the same procedure to configure these same devices as the fencing devices for clusternode2.example.com, specifying Port 2 on each switch for clusternode2.example.com:

On the status page for clusternode1.example.com in cluster apcclust, the other nodes in apcclust are displayed below the Configure menu item below the Nodes menu item on the left side of the screen. Click clusternode2.example.com to display the status screen for clusternode2.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
As for clusternode1.example.com, the fence device pwr01 should display as one of the menu options on the dropdown menu, under Use an Existing Fence Device. Select pwr01 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login, Password, Password Script values already configured, as defined when you configured pwr01 as a shared fence device.
For Port, enter 2. Do not enter any value for Switch.
Before clicking on Update main fence properties, click on Add a fence device to this level to add the fence device pwr02.
Select pwr02 (APC Power Device) from the Use an Existing Fence Device display of the dropdown menu. This causes a fence device configuration menu to display with the Name, IP Address, Login, Password, Password Script values already configured, as defined when you configured pwr01 as a shared fence device.
For Port, enter 2. Do not enter any value for Switch.
To configure both of the fence devices, Click Update main fence properties.

Similarly, configure pwr01 and pwr02 as the main fencing method for clusternode3.example.com, this time specifying 3 as the Port number for both devices.

6.4. Cluster Configuration File with Dual Power Supply Fencing

Configuring a cluster with Conga modifies the cluster configuration file. This section shows the cluster configuration file before and after the procedures documented in Section 6.3, “Dual Power Fencing Configuration Procedure” were performed.

Before the cluster resources and service were configured, the cluster.conf file appeared as follows.


<?xml version="1.0"?>
<cluster alias="apcclust" config_version="34" name="apcclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices/>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

After the cluster resources and service were configured, the cluster.conf file appears as follows.


<?xml version="1.0"?>
<cluster alias="apcclust" config_version="40" name="apcclust">
    <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
    <clusternodes>
          <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                  <fence>
                          <method name="1">
                                <device name="pwr01" option="off" port="1"/>
                                <device name="pwr02" option="off" port="1"/>
                                <device name="pwr01" option="on" port="1"/>
                                <device name="pwr02" option="on" port="1"/>
                          </method>
                  </fence>
          </clusternode>
          <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                  <fence>
                          <method name="1">
                                <device name="pwr01" option="off" port="2"/>
                                <device name="pwr02" option="off" port="2"/>
                                <device name="pwr01" option="on" port="2"/>
                                <device name="pwr02" option="on" port="2"/>
                          </method>
                  </fence>
          </clusternode>
          <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                  <fence>
                          <method name="1">
                                <device name="pwr01" option="off" port="3"/>
                                <device name="pwr02" option="off" port="3"/>
                                <device name="pwr01" option="on" port="3"/>
                                <device name="pwr02" option="on" port="3"/>
                          </method>
                  </fence>
            </clusternode>
    </clusternodes>
    <cman/>
    <fencedevices>
          <fencedevice agent="fence_apc" ipaddr="10.15.86.96" login="apclogin" name="pwr01" passwd="apcpword"/>
          <fencedevice agent="fence_apc" ipaddr="10.15.86.97" login="apclogin" name="pwr02" passwd="apcpword"/>
    </fencedevices>
    <rm>
          <failoverdomains/>
          <resources/>
    </rm>
</cluster>

6.5. Testing the Dual Power Fence Device Configuration

To test whether the dual power fencing configuration been successfully configured for the three nodes in cluster apcclust, execute the following commands and check whether the nodes have been fenced.

# /sbin/fence_node clusternode1.example.com
# /sbin/fence_node clusternode2.example.com
# /sbin/fence_node clusternode3.example.com

Chapter 7. Configuring a Backup Fencing Method

You can define multiple fencing methods for a node. If fencing fails using the first method, the system will attempt to fence the node using the second method. This chapter provides the procedures for using the Conga configuration tool in a Red Hat cluster to configure a main fencing method and a backup fencing method.

Figure 7.1, “Cluster Configured with Backup Fencing Method” shows the configuration this procedure yields. In this configuration, the main fencing method consists of two APC network power switches, each of which runs on its own separate UPS and has its own unique IP address. Each node in the cluster is connected to a port on each APC switch. As a backup fencing method, each node on this cluster is configured with an IPMI management board as a fencing device.

Note

Note that in this configuration each system has redundant power and is hooked into two independent power sources. This ensures that the IPMI management board in the node would still function as needed in a cluster even if you lose power from one of the sources.

Figure 7.1. Cluster Configured with Backup Fencing Method

7.1. Backup Fencing Prerequisite Configuration

Table 7.1, “Configuration Prerequisities” summarizes the prerequisite components that have been set up before this procedure begins.

Table 7.1. Configuration Prerequisities
Component	Name	Comment
cluster	backupclust	three-node cluster
cluster node	clusternode1.example.com	node in cluster backupclust configured with 2 APC switches, an IPMI management board, and 2 power supplies
cluster node	clusternode2.example.com	node in cluster backupclust configured with 2 APC switches, an IPMI management board, and 2 power supplies
cluster node	clusternode3.example.com	node in cluster backupclust configured with 2 APC switches, an IPMI management board, and 2 power supplies
IP address	10.15.86.96	IP address for the first APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com. This switch runs on its own UPS.
IP address	10.15.86.97	IP address for the second APC switch that controls the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com. This switch runs on its own UPS.
IP address	10.15.86.50	IP address for IPMI management board for clusternode1.example.com
IP address	10.15.86.51	IP address for IPMI management board for clusternode2.example.com
IP address	10.15.86.52	IP address for IPMI management board for clusternode3.example.com

Table 7.2, “Configuration Prerequisities” summarizes the prerequisite components that have been set up for each of the APC switches before this procedure begins.

Table 7.2. Configuration Prerequisities
Component	Name	Comment
login	apclogin	login value for both of the the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	apcpword	password for both the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
port	1	port number on both of the APC switches that clusternode1.example.com connects to
port	2	port number on both of the APC switches that clusternode2.example.com connects to
port	3	port number on both of the APC switches that clusternode3.example.com connects to

Table 7.3, “Configuration Prerequisities” summarizes the prerequisite components that have been set up for each of the IPMI management boards before this procedure begins.

Table 7.3. Configuration Prerequisities
Component	Name	Comment
login	ipmilogin	login name for IPMI management board for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	ipmipword	password IPMI management board for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com

7.2. Fence Device Components to Configure

This procedure consists of the following steps:

The procedure configures two APC switches as fence devices that will be used as the main fencing method for each node in cluster backupclust.
The procedure configures the main and backup fencing methods for clusternode1.example.com, using the two APC switches for the main fencing method for the node and using its IPMI management board as the backup fencing method for the node.
The procedure configures the main and backup fencing methods for clusternode2.example.com, using the two APC switches for the main fencing method for the node and using its IPMI management board as the backup fencing method for the node.
The procedure configures the main and backup fencing methods for clusternode3.example.com, using the two APC switches for the main fencing method for the node and using its IPMI management board as the backup fencing method for the node.

Table 7.4, “Fence Device Components to Configure for APC Fence Device” summarizes the components of the APC fence devices that this procedure configures for the nodes in the cluster backupclust.

Table 7.4. Fence Device Components to Configure for APC Fence Device
Fence Device Component	Value	Description
Fencing Type	APC Power Switch	type of fencing device to configure for each APC switch
Name	pwr01	name of the first APC fencing device for node1.example.com, node2.example.com, and node3.example.com
IP address	10.15.86.96	IP address of the first APC switch to configure as a fence device for node1.example.com, node2.example.com, and node3.example.com
Name	pwr02	name of the second APC fencing device for node1.example.com, node2.example.com, and node3.example.com
IP address	10.15.86.97	IP address of the second APC switch to configure as a fence device for node1.example.com, node2.example.com, and node3.example.com
login	apclogin	login value for the each of the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com
password	apcpword	password for each of the APC switches that control the power for for clusternode1.example.com, clusternode2.example.com, and clusternode3.example.com

Table 7.5, “Fence Agent Components to Specify for clusternode1.example.com” summarizes the components of the main and backup fence devices that you specify for the node clusternode1.example.com.

Table 7.5. Fence Agent Components to Specify for clusternode1.example.com
Fence Agent Component	Value	Description
fence device	pwr01	name of the first APC fence device you defined as a shared device
port	1	port number on the first APC switch for node1.example.com
fence device	pwr02	name of the second APC fence device you defined as a shared device
port	1	port number on the second APC switch for clusternode1.example.com
Name	ipmifence1	name of the IPMI fencing device for clusternode1.example.com
IP address	10.15.86.50	IP address of the IPMI management board for clusternode1.example.com
IPMI login	ipmilogin	login identity for the IPMI management board for clusternode1.example.com
password	ipmipword	password for the IPMI management board for clusternode1.example.com
authentication type	password	authentication type for the IPMI management board for clusternode1.example.com

Table 7.6, “Fence Agent Components to Specify for clusternode2.example.com” summarizes the components of the main and backup fence devices that you specify for the node clusternode2.example.com.

Table 7.6. Fence Agent Components to Specify for clusternode2.example.com
Fence Agent Component	Value	Description
fence device	pwr01	name of the first APC fence device you defined as a shared device
port	2	port number on the first APC switch for node2.example.com
fence device	pwr02	name of the second APC fence device you defined as a shared device
port	2	port number on the second APC switch for clusternode2.example.com
Name	ipmifence2	name of the IPMI fencing device for clusternode2.example.com
IP address	10.15.86.51	IP address of the IPMI management board for clusternode2.example.com
IPMI login	ipmilogin	login identity for the IPMI management board for clusternode2.example.com
password	ipmipword	password for the IPMI management board for clusternode2.example.com
authentication type	password	authentication type for the IPMI management board for clusternode2.example.com

Table 7.7, “Fence Agent Components to Specify for clusternode3.example.com” summarizes the components of the main and backup fence devices that you specify for the node clusternode3.example.com.

Table 7.7. Fence Agent Components to Specify for clusternode3.example.com
Fence Agent Component	Value	Description
fence device	pwr01	name of the first APC fence device you defined as a shared device
port	3	port number on the first APC switch for node3.example.com
fence device	pwr02	name of the second APC fence device you defined as a shared device
port	3	port number on the second APC switch for clusternode3.example.com
Name	ipmifence3	name of the IPMI fencing device for clusternode3.example.com
IP address	10.15.86.52	IP address of the IPMI management board for clusternode3.example.com
IPMI login	ipmilogin	login identity for the IPMI management board for clusternode3.example.com
password	ipmipword	password for the IPMI management board for clusternode3.example.com
authentication type	password	authentication type for the IPMI management board for clusternode3.example.com

7.3. Backup Fencing Configuration Procedure

This section provides the procedure for adding two APC fence devices to each node of cluster backupclust, configured as a single main fence method to ensure that the fencing is successful. This procedure also configures an IPMI management board as a backup fence device for each node of cluster backupclust.

This example uses the same APC switches for each cluster node. The APC switches will first be configured as shared fence devices. After configuring the APC switches as shared fence devices, the APC devices and the IPMI devices will be added as fence devices for each node in the cluster.

7.3.1. Configuring the APC switches as shared fence devices

To configure the first APC switch as a shared fence device named pwr01 using Conga, perform the following procedure:

As an administrator of luci Select the cluster tab. This displays the Choose a cluster to administer screen.
From the Choose a cluster to administer screen, you should see the previously configured cluster backupclust displayed, along with the nodes that make up the cluster. Click on backupclust to select the cluster.
At the detailed menu for the cluster backupclust (below the clusters menu on the left side of the screen), click Shared Fence Devices. Clicking Shared Fence Devices causes the display of any shared fence devices previously configured for a cluster and causes the display of menu items for fence device configuration: Add a Fence Device and Configure a Fence Device.
Click Add a Fence Device. Clicking Add a Fence Device causes the Add a Sharable Fence Device page to be displayed.
At the Add a Sharable Fence Device page, click the drop-down box under Fencing Type and select APC Power Switch. This causes Conga to display the components of an APC Power Switch fencing type, as shown in Figure 3.2, “Adding a Sharable Fence Device”.
Figure 7.2. Adding a Sharable Fence Device
For Name, enter pwr01.
For IP Address, enter 10.15.86.96.
For Login, enter apclogin.
For Password, enter apcpword.
For Password Script, leave blank.
Click Add this shared fence device.
Clicking Add this shared fence device temporarily displays a a progress page. After the fence device has been added, the detailed cluster properties menu is updated with the fence device under Configure a Fence Device.

To configure the second APC switch as a shared fence device named pwr02, perform the following procedure:

After configuring the first APC switch as shared fence device pwr01, click Add a Fence Device from the detailed menu for the cluster backupclust (below the clusters menu on the left side of the screen). This displays the Add a Sharable Fence Device page.
At the Add a Sharable Fence Device page, click the drop-down box under Fencing Type and select APC Power Switch. This causes Conga to display the components of an APC Power Switch fencing type.
For Name, enter pwr02.
For IP Address, enter 10.15.86.97.
For Login, enter apclogin.
For Password, enter apcpword.
For Password Script, leave blank.
Click Add this shared fence device.
Clicking Add this shared fence device causes a progress page to be displayed temporarily. After the fence device has been added, the detailed cluster properties menu is updated with the fence device under Configure a Fence Device.

7.3.2. Configuring Fencing on the First Cluster Node

After configuring the APC switches as shared fence devices, use the following procedure to configure the first APC switch, pwr01, as the first fence device for node clusternode1.example.com.

At the detailed menu for the cluster backupclust (below the clusters menu), click Nodes. Clicking Nodes causes the display of the status of each node in backupclust.
At the bottom of the display for node clusternode1.example.com, click Manage Fencing for this Node. This displays the configuration screen for node clusternode1.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown menu to display.
From the dropdown menu, the pwr01 and pwr02 fence devices you have already created should display as one of the menu options under Use an Existing Fence Device. Select pwr01 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login,Password, and Password Script values already configured, as defined when you configured pwr01 as a shared fence device. (The Password value does not display, but you may not alter it.) This is shown in Figure 7.3, “Adding Fence Device pwr01 to a Node”.
Figure 7.3. Adding Fence Device pwr01 to a Node
For Port, enter 1. Do not enter any value for Switch.

Before updating the main fence properties for this node, use the following procedure to add pwr02 as the second fence device of the main fencing method for node clusternode1.example.com.

Beneath the configuration information for pwr01 that you have entered, click Add a fence device to this level. This displays the dropdown menu again.
From the dropdown menu, select pwr02 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login,Password, and Password Script values already configured, as defined when you configured pwr02 as a shared fence device. This is shown in Figure 7.4, “Adding Fence Device pwr02 to a Node”.
Figure 7.4. Adding Fence Device pwr02 to a Node
For Port, enter 1. Do not enter any value for Switch.

After entering the configuration information for both power sources to use as fence devices, you can update the main fence properties using the following procedure.

Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, Click OK. A progress page is displayed after which the display returns to the status page for clusternode2.example.com in cluster backupclust.

After configuring the main fence method for clusternode1.example.com and updating the main fence properties, use the following procedure to configure the IPMI management board for node clusternode1.example.com as the backup fencing method for that node:

At the Backup Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Create a new Fence Device, select IPMI Lan. This displays a fence device configuration menu, as shown in Figure 7.5, “Configuring a Backup Fencing Method”.
Figure 7.5. Configuring a Backup Fencing Method
For Name, enter ipmifence1.
For IP Address, enter 10.15.86.50.
For Login, enter ipmilogin.
For Password, enter ipmipword.
For Password Script, leave the field blank.
For Authentication type, enterpassword. This field specifies the IPMI authentication type. Possible values for this field are none, password, md2, or md5.
Leave the Use Lanplus field blank. You would check this field if your fence device is a Lanplus-capable interface such as iLO2.

After entering the configuration information for the backup fencing method for clusternode1.example.com, you can update the backup fence properties using the following procedure.

Click Update backup fence properties at the bottom of the right side of the screen. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode1.example.com in cluster backupclust.

7.3.3. Configuring Fencing on the Remaining Cluster Nodes

After configuring the main fencing method and the backup fencing method for clusternode1.example.com, use the same procedure to configure the fencing methods for clusternode2.example.com and clusternode3.example.com.

At the detailed menu for the cluster backupclust (below the clusters menu on the left side of the screen) click on clusternode2.example.com, which should be displayed below Nodes -> Configure. This displays the configuration screen for node clusternode2.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown menu to display.
From the dropdown menu, the pwr01 and pwr02 fence devices you have already created should display as one of the menu options under Use an Existing Fence Device. Select pwr01 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login,Password, and Password Script values already configured, as defined when you configured pwr01 as a shared fence device. (The Password value does not display, but you may not alter it.)
For Port, enter 2. Do not enter any value for Switch.

Before updating the main fence properties for this node, use the following procedure to add pwr02 as the second fence device of the main fencing method for node clusternode1.example.com.

Beneath the configuration information for pwr01 that you have entered, click Add a fence device to this level. This displays the dropdown menu again.
From the dropdown menu, select pwr02 (APC Power Device). This causes a fence device configuration menu to display with the Name, IP Address, Login,Password, and Password Script values already configured, as defined when you configured pwr02 as a shared fence device.
For Port, enter 2. Do not enter any value for Switch.

After entering the configuration information for both power sources to use as fence devices, you can update the main fence properties using the following procedure.

Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, Click OK. A progress page is displayed after which the display returns to the status page for clusternode1.example.com in cluster backupclust.

After configuring the main fence method for clusternode2.example.com and updating the main fence properties, use the following procedure to configure the IPMI management board for node clusternode2.example.com as the backup fencing method for that node:

At the Backup Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Create a new Fence Device, select IPMI Lan. This displays a fence device configuration menu.
For Name, enter ipmifence1.
For IP Address, enter 10.15.86.51.
For Login, enter ipmilogin.
For Password, enter ipmipword.
For Password Script, leave the field blank.
For Authentication type, enterpassword. This field specifies the IPMI authentication type. Possible values for this field are none, password, md2, or md5.
Leave the Use Lanplus field blank.

After entering the configuration information for the backup fencing method for clusternode2.example.com, you can update the backup fence properties using the following procedure.

Click Update backup fence properties at the bottom of the right side of the screen. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode2.example.com in cluster backupclust.

To configure the fencing methods for clusternode3.example.com, use the same procedure as you did for configuring the fencing methods for clusternode2.example.com. In this case, however, use 3 as the port number for both of the APC switches that you are using for the main fencing method. For the backup fencing method, use ipmifence3 as the name of the fence type and use an IP address of 10.15.86.52. The other components should be the same, as summarized in Table 7.7, “Fence Agent Components to Specify for clusternode3.example.com”.

7.4. Cluster Configuration File for Backup Fence Method

Configuring a cluster with Conga modifies the cluster configuration file. This section shows the cluster configuration file before and after the procedures documented in Section 7.3, “Backup Fencing Configuration Procedure” were performed.

Before the cluster resources and service were configured, the cluster.conf file appeared as follows.


<?xml version="1.0"?>
<cluster alias="backupclust" config_version="34" name="backupclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices/>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

After the cluster resources and service were configured, the cluster.conf file appears as follows.


<?xml version="1.0"?>
<cluster alias="backupclust" config_version="10" name="backupclust">
    <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
    <clusternodes>
        <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                <fence>
                     <method name="1">
                          <device name="pwr01" option="off" port="1"/>
                          <device name="pwr02" option="off" port="1"/>
                          <device name="pwr01" option="on" port="1"/>
                          <device name="pwr02" option="on" port="1"/>
                     </method>
                     <method name="2">
                          <device name="ipmifence1"/>
                     </method>
                </fence>
        </clusternode>
        <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                <fence>
                     <method name="1">
                          <device name="pwr01" option="off" port="2"/>
                          <device name="pwr02" option="off" port="2"/>
                          <device name="pwr01" option="on" port="2"/>
                          <device name="pwr02" option="on" port="2"/>
                     </method>
                     <method name="2">
                          <device name="ipmifence2"/>
                     </method>
                </fence>
        </clusternode>
        <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                <fence>
                     <method name="1">
                          <device name="pwr01" option="off" port="3"/>
                          <device name="pwr02" option="off" port="3"/>
                          <device name="pwr01" option="on" port="3"/>
                          <device name="pwr02" option="on" port="3"/>
                 </method>
                         <method name="2">
                          <device name="ipmifence3"/>
                     </method>
                </fence>
        </clusternode>
    </clusternodes>
    <cman/>
    <fencedevices>
        <fencedevice agent="fence_apc" ipaddr="10.15.86.96" login="apclogin" name="pwr01" passwd="apcpword"/>
        <fencedevice agent="fence_apc" ipaddr="10.15.86.97" login="apclogin" name="pwr02" passwd="apcpword"/>
        <fencedevice agent="fence_ipmilan" ipaddr="10.15.86.50" login="ipmilogin" name="ipmifence1" passwd="ipmipword"/>
        <fencedevice agent="fence_ipmilan" ipaddr="10.15.86.51" login="ipmilogin" name="ipmifence2" passwd="ipmipword"/>
        <fencedevice agent="fence_ipmilan" ipaddr="10.15.86.52" login="ipmilogin" name="ipmifence3" passwd="ipmipword"/>
    </fencedevices>
    <rm>
            <failoverdomains/>
            <resources/>
    </rm>
</cluster>

7.5. Testing the Backup Fence Device Configuration

To check whether the configuration you have defined works as expected, you can first try simply fencing the nodes to see if any issues arise:

# /sbin/fence_node clusternode1.example.com
# /sbin/fence_node clusternode2.example.com
# /sbin/fence_node clusternode3.example.com

To see whether the backup IPMI fencing will work when the primary APC switch fencing does not, disable the ethernet access to both APC switches. This will prevent the fence_node command from being able to access the switches. Then run the fence_node command on each node in the cluster to see whether the IPMI switch takes over and fences the node.

Chapter 8. Configuring Fencing using SCSI Persistent Reservations

This chapter provides the procedures for configuring fencing using SCSI persistent reservations in a Red Hat cluster using the Conga configuration tool.

SCSI persistent reservations provide the capability to control the access of each node to shared storage devices. Red Hat Cluster Suite employs SCSI persistent reservations as a fencing methods through the use of the fence_scsi agent. The fence_scsi agent provides a method to revoke access to shared storage devices, provided that the storage support SCSI persistent reservations.

Using SCSI reservations as a fencing method is different from traditional power fencing methods. It is important to understand the software, hardware, and configuration requirements prior to using SCSI persistent reservations as a fencing method.

8.1. Technical Overview of SCSI Persistent Reservations

In order to understand how Red Hat Cluster Suite is able to use SCSI persistent reservations as a fencing method, it is helpful to have some basic knowledge of SCSI persistent reservations.

There are two important concepts withing SCSI persistent reservations that should be made clear: registrations and reservations.

8.1.1. SCSI Registrations

A registration occurs when a node registers a unique key with a device. A device can have many registrations. For our purposes, each node will create a registration on each device.

8.1.2. SCSI Technical Overview

A reservation dictates how a device can be accessed. In contrast to registrations, there can be only one reservation on a device at any time. The node that holds the reservation is know as the "reservation holder". The reservation defines how other nodes may access the device. For example, Red Hat Cluster Suite uses a "Write Exclusive, Registrants Only" reservation. This type of reservation indicates that only nodes that have registered with that device may write to the device.

8.1.3. SCSI Fencing with Persistent Reservations

Red Hat Cluster Suite is able to perform fencing via SCSI persistent reservations by simply removing a node's registration key from all devices. When a node failure occurs, the fence_scsi agent will remove the failed node's key from all devices, thus preventing it from being able to write to those devices.

8.2. SCSI Fencing Requirements and Limitations

In order to configure your system to use SCSI persistent reservations to fence a node, you must be sure that the following conditions are met.

The sg3_utils package must be installed on your cluster nodes. This package provides the tools needed by the various scripts to manage SCSI persistent reservations.
All shared storage must use LVM2 cluster volumes.
All devices within the LVM2 cluster volumes must be SPC-3 compliant.

In addition to these requirements, fencing by way of SCSI persistent reservations is subject to the following limitations:

All nodes in the cluster must have a consistent view of storage. Each node in the cluster must be able to remove another node's registration key from all the devices that it registered with. In order to do this, the node performing the fencing operation must be aware of all devices that other nodes are registered with.
Devices used for the cluster volumes should be a complete LUN, not partitions. SCSI persistent reservations work on an entire LUN, meaning that access is controlled to each LUN, not individual partitions.
As of Red Hat Enterprise Linux 5.5 and fully-updated releases of Red Hat Enterprise Linux 5.4, SCSI fencing can be used in a 2-node cluster; previous releases did not support this feature.
As of Red Hat Enterprise Linux 5.5 and fully-updated releases of Red Hat Enterprise Linux 5.4, SCSI fencing can be used in conjunction with qdisk; previous releases did not support this feature. You cannot use fence_scsi on the LUN where qdiskd resides; it must be a raw LUN or raw partition of a LUN.

8.3. SCSI Fencing Example Configuration

Figure 8.1, “Using SCSI Persistent Reservations as a Fence Device” shows the configuration this procedure yields. All three nodes in this cluster have a consistent view of the storage, which means in this case that all of the nodes are registered with the same devices.

Figure 8.1. Using SCSI Persistent Reservations as a Fence Device

8.4. SCSI Fencing Prerequisite Configuration

Table 8.1, “Configuration Prerequisities” summarizes the prequisite components that have been set up before this procedure begins.

Table 8.1. Configuration Prerequisities
Component	Name	Comment
cluster	scsiclust	three-node cluster
cluster node	clusternode1.example.com	node in cluster scsiclust with `sg3_utils` package installed
cluster node	clusternode2.example.com	node in cluster scsiclust with `sg3_utils` package installed
cluster node	clusternode3.example.com	node in cluster scsiclust with `sg3_utils` package installed

8.5. SCSI Fence Device Components to Configure

This procedure configures SCSI persistent reservations as a fence method for each node in cluster scsiclust.

Table 8.2, “Fence Agent Components to Configure for clusternode1.example.com” summarizes the components of the SCSI fence device that this procedure configures for cluster node clusternode1.example.com.

Table 8.2. Fence Agent Components to Configure for clusternode1.example.com
Fence Agent Component	Value	Description
Name	scsifence	name of the SCSI fencing device
Node name	node1	name of node to be fenced

Table 8.3, “Fence Agent Components to Configure for clusternode2.example.com” summarizes the components of the scsi fence device that this procedure configures for cluster node clusternode2.example.com.

Table 8.3. Fence Agent Components to Configure for clusternode2.example.com
Fence Agent Component	Value	Description
Name	scsifence	name of the SCSI fencing device
Node name	node2	name of node to be fenced

Table 8.4, “Fence Agent Components to Configure for clusternode3.example.com” summarizes the components of the SCSI fence device that this procedure configures for cluster node clusternode3.example.com.

Table 8.4. Fence Agent Components to Configure for clusternode3.example.com
Fence Agent Component	Value	Description
Name	scsifence	name of the SCSI fencing device
Node name	node3	name of node to be fenced

8.6. SCSI Fence Device Configuration Procedure

This section provides the procedure for configuring SCSI persistent reservations as a fencing mechanism for each node of cluster scsiclust.

Use the following procedure to configure the HP iLO management board as the fence device for node clusternode1.example.com using Conga:

As an administrator of luci Select the cluster tab. This displays the Choose a cluster to administer screen.
From the Choose a cluster to administer screen, you should see the previously configured cluster scsiclust displayed, along with the nodes that make up the cluster. Click on clusternode1.example.com. This displays the configuration screen for node clusternode1.example.com.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown menu to display.
From the dropdown menu, under Create a new Fence Device, select SCS fencing. This displays a fence device configuration menu.
For Name, enter scsifence.
For Node name, enter node1.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode1.example.com in cluster scsiclust.

After configuring a SCSI fence device for clusternode1.example.com, use the following procedure to configure a SCSI fence device for clusternode2.example.com.

From the configuration page for clusternode1.example.com, a menu appears on the left of the screen for cluster scsiclust. Select the node clusternode2.example.com. The configuration page for clusternode2.example.com appears, with no fence device configured.
At the Main Fencing Method display, click Add a fence device to this level. This causes a dropdown manu to display.
From the dropdown menu, under Use an existing Fence Device, you should see scsifence (SCSI Reservation), which you defined for clusternode1.example.com. Select this existing device, which displays a fence device configuration menu.
For Node Name, enter node2.
Click Update main fence properties. This causes a confirmation screen to be displayed.
On the confirmation screen, click OK. After the fence device has been added, a progress page is displayed after which the display returns to the configuration page for clusternode2.example.com in cluster scsiclust.

After configuring scsifence as the fencing device for clusternode2.example.com, select node clusternode3.example.com from the menu on the left side of the page and configure a SCSI fence device for that node using the same procedure as you did to configure the fence devices for clusternode2.example.com. For clusternode3.example.com , use the existing fence method scsifence as the name of the fencing method and node3 as the host name.

8.7. Cluster Configuration File with SCSI Fence Device

Configuring a cluster with Conga modifies the cluster configuration file. This section shows the cluster configuration file before and after the procedures documented in Section 8.6, “SCSI Fence Device Configuration Procedure” and were performed.

Before the cluster resources and service were configured, the cluster.conf file appeared as follows.


<?xml version="1.0"?>
<cluster alias="scsiclust" config_version="12" name="scsiclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence/>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        <fence>
                                <method name="1"/>
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices/>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

After the cluster resources and service were configured, the cluster.conf file appears as follows.


<?xml version="1.0"?>
<cluster alias="scsiclust" config_version="19" name="scsiclust">
        <fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="3"/>
        <clusternodes>
                <clusternode name="clusternode1.example.com" nodeid="1" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="scsifence" node="node1"/>
                                </method>
                        </fence>
                </clusternode>
                <clusternode name="clusternode2.example.com" nodeid="2" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="scsifence" node="node2"/>
                                </method>
                        </fence>
                </clusternode>
                <clusternode name="clusternode3.example.com" nodeid="3" votes="1">
                        <fence>
                                <method name="1">
                                        <device name="scsifence" node="node3"/>
                                </method>
                        </fence>
                </clusternode>
        </clusternodes>
        <cman/>
        <fencedevices>
                <fencedevice agent="fence_scsi" name="scsifence"/>
        </fencedevices>
        <rm>
                <failoverdomains/>
                <resources/>
        </rm>
</cluster>

8.8. Testing the Configuration

It is important that all SCSI fencing requirements be met in order for your system to successfully fence a node using SCSI persistent reservations. The SCSI fencing requirements are noted in Section 8.2, “SCSI Fencing Requirements and Limitations”. To ensure that your system meets these requirements, you should test your configuration.

After the cluster.conf has been set up on all of the nodes in the system, you can perform the following procedure to verify that all of the requirements have been met for SCSI fencing and that the configuration is successful.

For every node in the cluster, you should verify that the necessary infrastructure is up and running:
- Ensure that the cluster infrastructure is up and running on every node in the cluster; you can check this with the cman_tool status command.
- Ensure that the clvmd daemon is running; you can check this with the service clvmd status command.
- Ensure that the scsi_reserve service has been turned on by executing the chkconfig scsi_reserve on command.

Set up cluster LVM volumes to test.

[root@tng3-1 ~]# pvcreate /dev/sda1 /dev/sdb1 /dev/sdc1

[root@tng3-1 ~]# vgcreate new_vol_group /dev/sda1 /dev/sdb1 /dev/sdc1

[root@tng3-1 ~]# lvcreate -L2G -n new_logical_volume new_vol_group

[root@tng3-1 ~]# gfs_mkfs -plock_nolock -j 1 /dev/new_vol_group/new_logical_volume

[root@tng3-1 ~]# mount /dev/new_vol_group/new_logical_volume /mnt

Run the scsi_reserve init script on all nodes, and then check to see whether this worked.

[root@clusternode1 ~]# service scsi_reserve start
[root@clusternode1 ~]# service scsi_reserve status
[root@clusternode2 ~]# service scsi_reserve start
[root@clusternode2 ~]# service scsi_reserve status
[root@clusternode3 ~]# service scsi_reserve start
[root@clusternode3 ~]# service scsi_reserve status

Execute the following commands and check whether the nodes have been fenced.

# /sbin/fence_node clusternode1.example.com
# /sbin/fence_node clusternode2.example.com
# /sbin/fence_node clusternode3.example.com

Chapter 9. Troubleshooting

The following is a list of some problems you may see regarding the configuration of fence devices as well as some suggestions for how to address these problems.

If your system does not fence a node automatically, you can try to fence the node from the command line using the fence_node command, as described at the end of each of the fencing configuration procedures. The fence_node performs I/O fencing on a single node by reading the fencing settings from the cluster.conf file for the given node and then running the configured fencing agent against the node. For example, the following command fences node clusternode1.example.com:
```
# /sbin/fence_node clusternode1.example.com
```
If the fence_node command is unsuccessful, you may have made an error in defining the fence device configuration. To determine whether the fencing agent itself is able to talk to the fencing device, you can execute the I/O fencing command for your fence device directly from the command line. As a first step, you can execute the with the -o status option specified. For example, if you are using an APC switch as a fencing agent, you can execute a command such as the following:
```
# /sbin/fence_apc -a (ipaddress) -l (login) ... -o status -v
```
You can also use the I/O fencing command for your device to fence the node. For example, for an HP ILO device, you can issue the following command:
```
# /sbin/fence_ilo -a myilo -l login -p passwd -o off -v
```
Check the version of firmware you are using in your fence device. You may want to consider upgrading your firmware. You may also want to scan bugzilla to see if there are any issues regarding your level of firmware.
If a node in your cluster is repeatedly getting fenced, it means that one of the nodes in your cluster is not seeing enough "heartbeat" network messages from the node that is getting fenced. Most of the time, this is a result of flaky or faulty hardware, such as bad cables or bad ports on the network hub or switch. Test your communications paths thoroughly without the cluster software running to make sure your hardware is working correctly.
If a node in your cluster is repeatedly getting fenced right at startup, if may be due to system activities that occur when a node joins a cluster. If your network is busy, your cluster may decide it is not getting enough heartbeat packets. To address this, you may have to increase the post_join_delay setting in your cluster.conf file. This delay is basically a grace period to give the node more time to join the cluster.
In the following example, the fence_daemon entry in the cluster configuration file shows a post_join_delay setting that has been increased to 600.
```
<fence_daemon clean_start="0" post_fail_delay="0" post_join_delay="600">
```
If a node fails while the fenced daemon is not running, it will not be fenced. It will cause problems if the fenced daemon is killed or exits while the node is using GFS. If the fenced daemon exits, it should be restarted.

If you find that you are seeing error messages when you try to configure your system, or if after configuration your system does not behave as expected, you can perform the following checks and examine the following areas.

Connect to one of the nodes in the cluster and execute the clustat(8) command. This command runs a utility that displays the status of the cluster. It shows membership information, quorum view, and the state of all configured user services.

The following example shows the output of the clustat(8) command.

[root@clusternode4 ~]# clustat
Cluster Status for nfsclust @ Wed Dec  3 12:37:22 2008
Member Status: Quorate

 Member Name                              ID   Status
 ------ ----                              ---- ------
 clusternode5.example.com          1 Online, rgmanager
 clusternode4.example.com          2 Online, Local, rgmanager
 clusternode3.example.com          3 Online, rgmanager
 clusternode2.example.com          4 Online, rgmanager
 clusternode1.example.com          5 Online, rgmanager

 Service Name             Owner (Last)                     State
 ------- ---              ----- ------                     -----
 service:nfssvc           clusternode2.example.com         starting

In this example, clusternode4 is the local node since it is the host from which the command was run. If rgmanager did not appear in the Status category, it could indicate that cluster services are not running on the node.

Connect to one of the nodes in the cluster and execute the group_tool(8) command. This command provides information that you may find helpful in debugging your system. The following example shows the output of the group_tool(8) command.
```
[root@clusternode1 ~]# group_tool
type             level name       id       state
fence            0     default    00010005 none
[1 2 3 4 5]
dlm              1     clvmd      00020005 none
[1 2 3 4 5]
dlm              1     rgmanager  00030005 none
[3 4 5]
dlm              1     mygfs      007f0005 none
[5]
gfs              2     mygfs      007e0005 none
[5]
```
The state of the group should be none. The numbers in the brackets are the node ID numbers of the cluster nodes in the group. The clustat shows which node IDs are associated with which nodes. If you do not see a node number in the group, it is not a member of that group. For example, if a node ID is not in dlm/rgmanager group, it is not using the rgmanager dlm lock space (and probably is not running rgmanager).
The level of a group indicates the recovery ordering. 0 is recovered first, 1 is recovered second, and so forth.
Connect to one of the nodes in the cluster and execute the cman_tool nodes -f command This command provides information about the cluster nodes that you may want to look at. The following example shows the output of the cman_tool nodes -f command.
```
[root@clusternode1 ~]# cman_tool nodes -f
Node  Sts   Inc   Joined               Name
   1   M    752   2008-10-27 11:17:15  clusternode5.example.com
   2   M    752   2008-10-27 11:17:15  clusternode4.example.com
   3   M    760   2008-12-03 11:28:44  clusternode3.example.com
   4   M    756   2008-12-03 11:28:26  clusternode2.example.com
   5   M    744   2008-10-27 11:17:15  clusternode1.example.com
```
The Sts heading indicates the status of a node. A status of M indicates the node is a member of the cluster. A status of X indicates that the node is dead. The Inc heading indicating the incarnation number of a node, which is for debugging purposes only.
Check whether the cluster.conf is identical in each node of the cluster. If you configure your system with Conga, as in the example provided in this document, these files should be identical, but one of the files may have accidentally been deleted or altered.

Chapter 10. The GFS Withdraw Function

The GFS withdraw function is a data integrity feature of GFS file systems in a cluster. If the GFS kernel module detects an inconsistency in a GFS file system following an I/O operation, the file system becomes unavailable to the cluster. The I/O operation stops and the system waits for further I/O operations to error out, preventing further damage. When this occurs, you can stop any other services or applications manually, after which you can reboot and remount the GFS file system to replay the journals. If the problem persists, you can unmount the file system from all nodes in the cluster and perform file system recovery with the gfs_fsck command. The GFS withdraw function is less severe than a kernel panic, which would cause another node to fence the node.

You can override the GFS withdraw function by mounting the file system with the -o errors=panic option specified. When this option is specified, any errors that would normally cause the system to withdraw cause the system to panic instead. This stops the node's cluster communications, which causes the node to be fenced.

For information on the GFS withdraw function, see Global File System: Configuration and Administration.

Appendix A. Revision History

Revision History

Revision 2-19.33.400

2013-10-31

Rüdiger Landmann

Rebuild with publican 4.0.0

Revision 2-19.33

July 24 2012

Ruediger Landmann

Rebuild for Publican 3.0

Revision 5.6-1

Thu Dec 10 2010

Steven Levine

Resolves: #581594

Updates information about support for qdisk with SCSI reservations.

Resolves: #622550

Updates information about support for SCSI reservations in a 2-node cluster.

Revision 2.0-0

Mon Mar 15 2010

Steven Levine

Added configuration examples for additional scenarios

Revision 1.0-0

Thu Jun 17 2009

Steven Levine

First edition

Index

A

APC fence device configuration

components to configure, APC Fence Device Components to Configure, Fence Device Components to Configure
prerequisites, APC Fence Device Prerequisite Configuration
procedure, APC Fence Device Configuration Procedure

APC switch

configuring as fence device, Configuring an APC Switch as a Fence Device
configuring as sharable fence device, APC Fence Device Configuration Procedure
testing fence configuration, Testing the APC Fence Device Configuration

APC switch configuration component

IP Address, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
Login, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
Name, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
Password, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
Password Script, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
Port, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring Fencing on the First Cluster Node
Switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring Fencing on the First Cluster Node
Use SSH, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring Fencing on the First Cluster Node

Authentication Type configuration component

HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

B

backup fence configuration

prerequisites, Backup Fencing Prerequisite Configuration

backup fence method

testing fence configuration, Testing the Backup Fence Device Configuration

backup fencing configuration, Configuring Fencing on the First Cluster Node

procedure, Backup Fencing Configuration Procedure

Backup Fencing Method configuration, Configuring Fencing on the First Cluster Node

C

clustat command, Troubleshooting
cluster.conf file, Cluster Configuration File with APC Fence Device, Cluster Configuration File with IPMI Fence Device, Cluster Configuration File with HP iLO Fence Device, Cluster Configuration File with Dual Power Supply Fencing, Cluster Configuration File for Backup Fence Method, Cluster Configuration File with SCSI Fence Device
cman_tool command, Troubleshooting

D

dual power

testing fence configuration, Testing the Dual Power Fence Device Configuration

dual power fence configuration

prerequisites, Dual Power Fencing Prerequisite Configuration

dual power fencing configuration, Dual Power Fencing Configuration Procedure

components to configure, Fence Device Components to Configure, Fence Device Components to Configure
procedure, Dual Power Fencing Configuration Procedure

F

fence device

APC switch, Configuring an APC Switch as a Fence Device
backup, Configuring a Backup Fencing Method
dual power, Configuring Fencing with Dual Power Supplies
HP iLO management board, Configuring HP ILO Management Boards as Fencing Devices
IPMI management board, Configuring IPMI Management Boards as Fencing Devices
SCSI persistent reservations, Configuring Fencing using SCSI Persistent Reservations

fence_apc command, Troubleshooting

fence_ilo command, Troubleshooting

fence_node command, Testing the APC Fence Device Configuration, Testing the IPMI Fence Device Configuration, Testing the HP iLO Fence Device Configuration, Testing the Dual Power Fence Device Configuration, Testing the Configuration, Troubleshooting

G

GFS withdraw function, The GFS Withdraw Function
group_tool command, Troubleshooting

H

HP iLO board configuration component

Authentication Type, HP iLO Fence Device Configuration Procedure
IP Address, HP iLO Fence Device Configuration Procedure
Login, HP iLO Fence Device Configuration Procedure
Name, HP iLO Fence Device Configuration Procedure
Password, HP iLO Fence Device Configuration Procedure
Password Script, HP iLO Fence Device Configuration Procedure
Use Lanplus, HP iLO Fence Device Configuration Procedure

HP iLO fence device configuration

components to configure, HP iLO Fence Device Components to Configure
prerequisites, HP iLO Fence Device Prerequisite Configuration
procedure, HP iLO Fence Device Configuration Procedure

HP iLO management board

configuring as fence device, Configuring HP ILO Management Boards as Fencing Devices
testing fence configuration, Testing the HP iLO Fence Device Configuration

I

IP Address configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

IPMI board configuration component

Authentication Type, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node
IP Address, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node
Login, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node
Name, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node
Password, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node
Password Script, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node
Use Lanplus, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

IPMI fence device configuration

components to configure, IPMI Fence Device Components to Configure, Fence Device Components to Configure
prerequisites, IPMI Fence Device Prerequisite Configuration
procedure, IPMI Fence Device Configuration Procedure

IPMI management board

configuring as fence device, Configuring IPMI Management Boards as Fencing Devices
testing fence configuration, Testing the IPMI Fence Device Configuration

L

Login configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

M

Main Fencing Method configuration, APC Fence Device Configuration Procedure, IPMI Fence Device Configuration Procedure, HP iLO Fence Device Configuration Procedure, SCSI Fence Device Configuration Procedure
main fencing method configuration, Configuring Fencing on the First Cluster Node, Configuring Fencing on the Remaining Cluster Nodes

N

Name configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

P

Password configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

Password Script configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring the APC switches as shared fence devices
HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

Port configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring Fencing on the First Cluster Node

post_join_delay setting in cluster.conf, Troubleshooting

S

SCSI fence device configuration

components to configure, SCSI Fence Device Components to Configure
prerequisites, SCSI Fencing Prerequisite Configuration
procedure, SCSI Fence Device Configuration Procedure

SCSI persistent reservations

configuring as fence device, Configuring Fencing using SCSI Persistent Reservations

sharable fence device

configuration, APC Fence Device Configuration Procedure

Switch configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring Fencing on the First Cluster Node

T

testing fence configuration

APC switch, Testing the APC Fence Device Configuration
backup method, Testing the Backup Fence Device Configuration
dual power, Testing the Dual Power Fence Device Configuration
HP iLO management board, Testing the HP iLO Fence Device Configuration
IPMI management board, Testing the IPMI Fence Device Configuration

U

Use Lanplus configuration component

HP iLO board, HP iLO Fence Device Configuration Procedure
IPMI board, IPMI Fence Device Configuration Procedure, Configuring Fencing on the First Cluster Node

Use SSH configuration component

APC switch, APC Fence Device Configuration Procedure, Dual Power Fencing Configuration Procedure, Configuring Fencing on the First Cluster Node

W

withdraw function, GFS, The GFS Withdraw Function

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Configuration Example - Fence Devices

Configuring Fence Devices in a Red Hat Cluster

Chapter 1. Introduction

1.1. About This Guide

1.2. Audience

1.3. Software Versions

1.4. Related Documentation

Chapter 2. Configuring Fence Devices in a Red Hat Cluster

Chapter 3. Configuring an APC Switch as a Fence Device

3.1. APC Fence Device Prerequisite Configuration

3.2. APC Fence Device Components to Configure

3.3. APC Fence Device Configuration Procedure

3.4. Cluster Configuration File with APC Fence Device

3.5. Testing the APC Fence Device Configuration

Chapter 4. Configuring IPMI Management Boards as Fencing Devices

4.1. IPMI Fence Device Prerequisite Configuration

4.2. IPMI Fence Device Components to Configure

4.3. IPMI Fence Device Configuration Procedure

4.4. Cluster Configuration File with IPMI Fence Device

4.5. Testing the IPMI Fence Device Configuration

Chapter 5. Configuring HP ILO Management Boards as Fencing Devices

5.1. HP iLO Fence Device Prerequisite Configuration

5.2. HP iLO Fence Device Components to Configure

5.3. HP iLO Fence Device Configuration Procedure

5.4. Cluster Configuration File with HP iLO Fence Device

5.5. Testing the HP iLO Fence Device Configuration

Chapter 6. Configuring Fencing with Dual Power Supplies

6.1. Dual Power Fencing Prerequisite Configuration

6.2. Fence Device Components to Configure

6.3. Dual Power Fencing Configuration Procedure

6.4. Cluster Configuration File with Dual Power Supply Fencing

6.5. Testing the Dual Power Fence Device Configuration

Chapter 7. Configuring a Backup Fencing Method

7.1. Backup Fencing Prerequisite Configuration

7.2. Fence Device Components to Configure

7.3. Backup Fencing Configuration Procedure

7.3.1. Configuring the APC switches as shared fence devices

7.3.2. Configuring Fencing on the First Cluster Node

7.3.3. Configuring Fencing on the Remaining Cluster Nodes

7.4. Cluster Configuration File for Backup Fence Method

7.5. Testing the Backup Fence Device Configuration

Chapter 8. Configuring Fencing using SCSI Persistent Reservations

8.1. Technical Overview of SCSI Persistent Reservations

8.1.1. SCSI Registrations

8.1.2. SCSI Technical Overview

8.1.3. SCSI Fencing with Persistent Reservations

8.2. SCSI Fencing Requirements and Limitations

8.3. SCSI Fencing Example Configuration

8.4. SCSI Fencing Prerequisite Configuration

8.5. SCSI Fence Device Components to Configure

8.6. SCSI Fence Device Configuration Procedure

8.7. Cluster Configuration File with SCSI Fence Device

8.8. Testing the Configuration

Chapter 9. Troubleshooting

Chapter 10. The GFS Withdraw Function

Appendix A. Revision History

Index

A

B

C

D

F

G

H

I

L

M

N

P

S

T

U

W

Legal Notice

Aprender

Pruebe, compre y venda

Comunidades

Acerca de la documentación de Red Hat

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