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Chapter 10. The Ceph iSCSI Gateway (Limited Availability)
As a storage administrator, you can install and configure an iSCSI gateway for the Red Hat Ceph Storage cluster. With Ceph’s iSCSI gateway you can effectively run a fully integrated block-storage infrastructure with all features and benefits of a conventional Storage Area Network (SAN).
This technology is Limited Availability. See the Deprecated functionality chapter for additional information.
SCSI persistent reservations are not supported. Mapping multiple iSCSI initiators to an RBD image is supported, if using a cluster aware file system or clustering software that does not rely on SCSI persistent reservations. For example, VMware vSphere environments using ATS is supported, but using Microsoft’s clustering server (MSCS) is not supported.
10.1. Introduction to the Ceph iSCSI gateway
Traditionally, block-level access to a Ceph storage cluster has been limited to QEMU and librbd
, which is a key enabler for adoption within OpenStack environments. Block-level access to the Ceph storage cluster can now take advantage of the iSCSI standard to provide data storage.
The iSCSI gateway integrates Red Hat Ceph Storage with the iSCSI standard to provide a highly available (HA) iSCSI target that exports RADOS Block Device (RBD) images as SCSI disks. The iSCSI protocol allows clients, known as initiators, to send SCSI commands to SCSI storage devices, known as targets, over a TCP/IP network. This allows for heterogeneous clients, such as Microsoft Windows, to access the Red Hat Ceph Storage cluster.
Figure 10.1. Ceph iSCSI Gateway
10.2. Requirements for the iSCSI target
The Red Hat Ceph Storage Highly Available (HA) iSCSI gateway solution has requirements for the number of gateway nodes, memory capacity, and timer settings to detect down OSDs.
Required Number of Nodes
Install a minimum of two iSCSI gateway hosts. To increase resiliency and I/O handling, install up to four iSCSI gateway hosts.
Memory Requirements
The memory footprint of the RBD images can grow to a large size. Each RBD image mapped on the iSCSI gateway hosts uses roughly 90 MB of memory. Ensure the iSCSI gateway hosts have enough memory to support each mapped RBD image.
Detecting Down OSDs
There are no specific iSCSI gateway options for the Ceph Monitors or OSDs, but it is important to lower the default timers for detecting down OSDs to reduce the possibility of initiator timeouts.
Additional Resources
- See the Red Hat Ceph Storage Hardware Selection Guide for more information.
10.3. Installing the iSCSI gateway
As a storage administrator, before you can utilize the benefits of the Ceph iSCSI gateway, you must install the required software packages. You can install the Ceph iSCSI gateway by using the command-line interface.
Each iSCSI gateway runs the Linux I/O target kernel subsystem (LIO) to provide iSCSI protocol support. LIO utilizes a user-space passthrough (TCMU) to interact with the Ceph librbd
library to expose RBD images to iSCSI clients. With the Ceph iSCSI gateway you can effectively run a fully integrated block-storage infrastructure with all features and benefits of a conventional Storage Area Network (SAN).
10.3.1. Prerequisites
- Red Hat Enterprise Linux 8.4 or higher.
- A running Red Hat Ceph Storage 5 or higher cluster.
10.3.2. Installing the Ceph iSCSI gateway using the command-line interface
The Ceph iSCSI gateway is the iSCSI target node and also a Ceph client node. The Ceph iSCSI gateway can be a standalone node or be colocated on a Ceph Object Store Disk (OSD) node. Complete the following steps to install the Ceph iSCSI gateway.
Prerequisites
- Red Hat Enterprise Linux 8.4 or higher
- A Red Hat Ceph Storage 5 cluster or higher
-
If the Ceph iSCSI gateway is not colocated on an OSD node, copy the Ceph configuration files, located in the
/etc/ceph/
directory, from a running Ceph node in the storage cluster to the all iSCSI gateway hosts. The Ceph configuration files must exist on the iSCSI gateway hosts under/etc/ceph/
. - On all Ceph iSCSI gateway hosts, enable the Ceph Tools repository.
- On all Ceph iSCSI gateway hosts, install and configure the Ceph command-line interface.
- If needed, open TCP ports 3260 and 5000 on the firewall on all Ceph iSCSI nodes.
- Create a new or use an existing RADOS Block Device (RBD).
Procedure
Retrieve the information of the iSCSI container on the host:
Example
[root@iscsigw ~]# podman ps
Log into the Cephadm shell:
Example
[root@iscsigw ~]# cephadm shell
Optional: On all Ceph iSCSI gateway hosts, install and configure the OpenSSL utility, if needed.
Install the
openssl
package:Example
[ceph: root@iscsigw /]# yum install openssl
On the primary iSCSI gateway node, create a directory to hold the SSL keys:
Example
[ceph: root@iscsigw /]# mkdir ~/ssl-keys [ceph: root@iscsigw /]# cd ~/ssl-keys
On the primary iSCSI gateway node, create the certificate and key files. Enter the environmental information when prompted.
Example
[ceph: root@iscsigw /]# openssl req -newkey rsa:2048 -nodes -keyout iscsi-gateway.key -x509 -days 365 -out iscsi-gateway.crt
On the primary iSCSI gateway node, create a PEM file:
Example
[ceph: root@iscsigw /]# cat iscsi-gateway.crt iscsi-gateway.key > iscsi-gateway.pem
On the primary iSCSI gateway node, create a public key:
Example
[ceph: root@iscsigw /]# openssl x509 -inform pem -in iscsi-gateway.pem -pubkey -noout > iscsi-gateway-pub.key
-
From the primary iSCSI gateway node, copy the
iscsi-gateway.crt
,iscsi-gateway.pem
,iscsi-gateway-pub.key
, andiscsi-gateway.key
files to the/etc/ceph/
directory on the other iSCSI gateway hosts.
Create a pool using the following commands:
Syntax
ceph osd pool create POOL_NAME PG_NUM ceph osd pool application enable POOL_NAME rbd rbd pool init -p POOL_NAME
Example
[ceph: root@iscsigw /]# ceph osd pool create pool1 100 [ceph: root@iscsigw /]# ceph osd pool application enable pool1 rbd [ceph: root@iscsigw /]# rbd pool init -p pool1
Create a configuration file on a Ceph iSCSI gateway node.
Create a file named
iscsi-gateway.yaml
in the/etc/ceph/
directory:Example
[ceph: root@iscsigw /]# touch /etc/ceph/iscsi-gateway.yaml
Edit the
iscsi-gateway.yaml
file and add the following lines:Syntax
service_type: iscsi service_id: iscsi placement: hosts: - HOST_NAME - HOST_NAME spec: pool: POOL_NAME # RADOS pool where ceph-iscsi config data is stored. trusted_ip_list: "IP_ADDRESS_1,IP_ADDRESS_2"
Example
service_type: iscsi service_id: iscsi placement: hosts: - host01 - host02 spec: pool: iscsipool1 trusted_ip_list: "10.80.100.100,10.8.100.113"
Change the path to
/etc/ceph/
and apply the specification with the following command:Example
[ceph: root@iscsigw /]# ceph orch apply -i iscsi-gateway.yaml
- Next, configure targets, LUNs, and clients. See the Configuring the iSCSI target using the command-line interface section for details.
Additional Resources
- See the iSCSI Gateway variables section for more details on the options.
- Creating iSCSI targets on the Ceph dashboard
10.4. Configuring the iSCSI target
As a storage administrator, you can configure targets, LUNs, and clients, using the gwcli
command-line utility. You can also optimize performance of the iSCSI target, use the gwcli reconfigure
subcommand.
Red Hat does not support managing Ceph block device images exported by the Ceph iSCSI gateway tools, such as gwcli
.. Also, using the rbd
command to rename or remove RBD images exported by the Ceph iSCSI gateway, can result in an unstable storage cluster.
Before removing RBD images from the iSCSI gateway configuration, follow the standard procedures for removing a storage device from the operating system. For details, see the Removing a storage device chapter in the Storage Administration Guide for Red Hat Enterprise Linux 7 or the System Design Guide for Red Hat Enterprise Linux 8.
10.4.1. Prerequisites
- Installation of the Ceph iSCSI gateway software.
10.4.2. Configuring the iSCSI target using the command-line interface
The Ceph iSCSI gateway is the iSCSI target node and also a Ceph client node. Configure the Ceph iSCSI gateway either on a standalone node, or colocate it with a Ceph Object Storage Device (OSD) node.
Do not adjust other options using the gwcli reconfigure
subcommand unless specified in this document or Red Hat Support has instructed you to do so.
Prerequisites
- Installation of the Ceph iSCSI gateway software.
Procedure
Retrieve the information of the iSCSI container running on the host:
Example
[root@iscsigw ~]# podman ps [root@iscsigw ~]# podman exec -it 4b5ffb814409 /bin/bash
Start the iSCSI gateway command-line interface:
[root@iscsigw ~]# gwcli
Navigate to the
iscsi-targets
directory:Example
/>cd /iscsi-targets
Create the iSCSI gateways using either IPv4 or IPv6 addresses:
Syntax
/>iscsi-targets create iqn.2003-01.com.redhat.iscsi-gw:_TARGET_NAME_ > goto gateways > create ISCSI_GW_NAME IP_ADDR_OF_GW > create ISCSI_GW_NAME IP_ADDR_OF_GW
Example
/>iscsi-targets create iqn.2003-01.com.redhat.iscsi-gw:ceph-igw > goto gateways > create ceph-gw-1 10.172.19.21 > create ceph-gw-2 10.172.19.22
Add a Ceph block device:
Syntax
> cd /disks />disks/ create POOL_NAME image=IMAGE_NAME size=IMAGE_SIZE_m|g|t
Example
> cd /disks />disks/ create rbd image=disk_1 size=50g
NoteDo not use any periods (
.
) in the pool or image name.Create a client:
Syntax
> goto hosts > create iqn.1994-05.com.redhat:_client_name_ > auth username=USER_NAME password=PASSWORD
Example
> goto hosts > create iqn.1994-05.com.redhat:rh7-client > auth username=iscsiuser1 password=temp12345678
ImportantRed Hat does not support mixing clients, some with Challenge Handshake Authentication Protocol (CHAP) enabled and some CHAP disabled. All clients must have either CHAP enabled or have CHAP disabled. The default behavior is to only authenticate an initiator by its initiator name.
If initiators are failing to log into the target, the CHAP authentication might not be configured correctly for some initiators, for example:
o- hosts ................................ [Hosts: 2: Auth: MISCONFIG]
Use the following command at the
hosts
level to reset all the CHAP authentication:/> goto hosts /iscsi-target...csi-igw/hosts> auth nochap ok ok /iscsi-target...csi-igw/hosts> ls o- hosts ................................ [Hosts: 2: Auth: None] o- iqn.2005-03.com.ceph:esx ........... [Auth: None, Disks: 4(310G)] o- iqn.1994-05.com.redhat:rh7-client .. [Auth: None, Disks: 0(0.00Y)]
Add disks to a client:
Syntax
/>iscsi-target..eph-igw/hosts > cd iqn.1994-05.com.redhat:_CLIENT_NAME_ > disk add POOL_NAME/IMAGE_NAME
Example
/>iscsi-target..eph-igw/hosts > cd iqn.1994-05.com.redhat:rh7-client > disk add rbd/disk_1
Verify that the Ceph ISCSI gateways are working:
/> goto gateways /iscsi-target...-igw/gateways> ls o- gateways ............................ [Up: 2/2, Portals: 2] o- ceph-gw-1 ........................ [ 10.172.19.21 (UP)] o- ceph-gw-2 ........................ [ 10.172.19.22 (UP)]
If the status is
UNKNOWN
, check for network issues and any misconfigurations. If using a firewall, verify that the appropriate TCP port is open. Verify that the iSCSI gateway is listed in thetrusted_ip_list
option. Verify that therbd-target-api
service is running on the iSCSI gateway node.Optionally, reconfigure the
max_data_area_mb
option:Syntax
/>disks/ reconfigure POOL_NAME/IMAGE_NAME max_data_area_mb NEW_BUFFER_SIZE
Example
/>disks/ reconfigure rbd/disk_1 max_data_area_mb 64
NoteThe
max_data_area_mb
option controls the amount of memory in megabytes that each image can use to pass SCSI command data between the iSCSI target and the Ceph cluster. If this value is too small, it can result in excessive queue full retries which will affect performance. If the value is too large, it can result in one disk using too much of the system memory, which can cause allocation failures for other subsystems. The default value for themax_data_area_mb
option is8
.- Configure an iSCSI initiator.
Additional Resources
- See Installing the iSCSI gateway for details.
- See Configuring the iSCSI initiator section for more information.
10.4.3. Optimize the performance of the iSCSI Target
There are many settings that control how the iSCSI Target transfers data over the network. These settings can be used to optimize the performance of the iSCSI gateway.
Only change these settings if instructed to by Red Hat Support or as specified in this document.
The gwcli reconfigure
subcommand controls the settings that are used to optimize the performance of the iSCSI gateway.
Settings that affect the performance of the iSCSI target
max_data_area_mb
- Description
- The size of kernel data ring buffer in megabytes.
- Type
- Integer
- Default
-
8
cmdsn_depth
- Description
- Indicates the depth of the queue that controls maximum I/O.
- Type
- Integer
- Default
-
128
immediate_data
- Description
-
Indicates if the initiator requests permission from the target to transmit immediate data whenever it establishes a new session. If this value is
Yes
, the initiator requests permission from the target to transmit immediate data whenever it establishes a new session. - Type
- Boolean
- Default
-
Yes
initial_r2t
- Description
-
Indicates if the host bus adapter (HBA) initiator requests permission from the target to transmit unsolicited SCSI data whenever it establishes a new session. If this member is
Yes
, the HBA initiator requests permission from the target to transmit unsolicited SCSI data whenever it establishes a new session. - Type
- Boolean
- Default
-
Yes
max_outstanding_r2t
- Description
- The maximum number of outstanding ready to transfer (R2T) requests for each task, excluding the first R2T that initiates the task.
- Type
- Integer
- Default
-
1
first_burst_length
- Description
- The maximum amount of unsolicited data an iSCSI initiator can send to the target during the execution of a single SCSI command.
- Type
- Integer in bytes
- Default
-
262144
max_burst_length
- Description
- The maximum SCSI data payload in an input PDU sequence or a solicited output PDU sequence.
- Type
- Integer in bytes
- Default
-
524288
max_recv_data_segment_length
- Description
- The maximum number of data bytes the initiator can receive in an iSCSI PDU from a target.
- Type
- Integer in bytes
- Default
-
262144
max_xmit_data_segment_length
- Description
- The maximum number of data bytes the initiator sends in an iSCSI PDU to the target.
- Type
- Integer in bytes
- Default
-
0
Additional Resources
-
Information about
max_data_area_mb
, including an example showing how to adjust it usinggwcli reconfigure
, is in the section Configuring the iSCSI Target using the Command Line Interface.
10.4.4. Configuring iSCSI host groups using the command-line interface
The Ceph iSCSI gateway can configure host groups for managing multiple servers that share the same disk configuration. iSCSI host groups creates a logical grouping of hosts and the disks that each host in the group has access to.
The sharing of disk devices to multiple hosts must use a cluster-aware file system.
Prerequisites
- Installation of the Ceph iSCSI gateway software.
- Root-level access to the Ceph iSCSI gateway node.
Procedure
Retrieve the information of the iSCSI container running on the host:
Example
[root@iscsigw ~] podman ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 4b5ffb814409 registry.redhat.io/rhceph-alpha/rhceph-5-rhel8:latest 2 hours ago Up 2 hours ago ceph-f838eb7a-597c-11eb-b0a9-525400e2439c-iscsi.iscsi.cephLab2-node-01.anaahg
Use the iSCSI container ID to enter into the container:
Example
[root@iscsigw ~]# podman exec -it 4b5ffb814409 /bin/bash
Run the
gwcli
command:[ceph: root@iscsigw /]# gwcli
Create a new host group:
Syntax
cd iscsi-targets/ cd IQN/host-groups create group_name=GROUP_NAME
Example
/> cd iscsi-targets/ /iscsi-targets> cd iqn.2003-01.com.redhat.iscsi-gw:ceph-igw/host-groups/ /iscsi-target.../host-groups> create group_name=igw_grp01
Add a host to the host group:
ImportantEnsure that you remove all the disks that are added to the host, before adding the host to the host group otheriwse, a host cannot be added to the hostgroup.
Syntax
cd GROUP_NAME host add client_iqn=CLIENT_IQN
Example
> cd igw_grp01 /iscsi-target.../host-groups/igw_grp01> host add client_iqn=iqn.1994-05.com.redhat:rh8-client
Repeat this step to add additional hosts to the group.
Add a disk to the host group:
Syntax
cd /disks/ /disks> create pool=POOL image=IMAGE_NAME size=SIZE cd /IQN/host-groups/GROUP_NAME disk add POOL/IMAGE_NAME
Example
> cd /disks/ /disks> create pool=rbd image=rbdimage size=1G /> cd iscsi-targets/iqn.2003-01.com.redhat.iscsi-gw:ceph-igw/host-groups/igw_grp01/ /iscsi-target...s/igw_grp01> disk add rbd/rbdimage
Repeat this step to add additional disks to the group.
10.4.5. Additional Resources
- For details on configuring iSCSI targets using the Red Hat Ceph Storage Dashboard, see the Creating iSCSI targets section in the Red Hat Ceph Storage Dashboard Guide.
10.5. Configuring the iSCSI initiator
You can configure the iSCSI initiator to connect to the Ceph iSCSI gateway on the following platforms.
10.5.1. Configuring the iSCSI initiator for Red Hat Enterprise Linux
Prerequisites
- Red Hat Enterprise Linux 7.7 or higher.
-
Package
iscsi-initiator-utils-6.2.0.873-35
or newer must be installed. -
Package
device-mapper-multipath-0.4.9-99
or newer must be installed.
Procedure
Install the iSCSI initiator and multipath tools:
[root@rhel ~]# yum install iscsi-initiator-utils [root@rhel ~]# yum install device-mapper-multipath
-
Set the initiator name by editing the
/etc/iscsi/initiatorname.iscsi
file. Note that the initiator name must match the initiator name that was used during the initial setup using thegwcli
command. Configure multipath I/O.
Create the default
/etc/multipath.conf
file and enable themultipathd
service:[root@rhel ~]# mpathconf --enable --with_multipathd y
Update the
/etc/multipath.conf
file as follows:devices { device { vendor "LIO-ORG" product "TCMU device" hardware_handler "1 alua" path_grouping_policy "failover" path_selector "queue-length 0" failback 60 path_checker tur prio alua prio_args exclusive_pref_bit fast_io_fail_tmo 25 no_path_retry queue } }
Restart the
multipathd
service:[root@rhel ~]# systemctl reload multipathd
Set up CHAP and iSCSI discovery and login.
Provide a CHAP user name and password by updating the
/etc/iscsi/iscsid.conf
file accordingly, for example:node.session.auth.authmethod = CHAP node.session.auth.username = user node.session.auth.password = password
Discover the target portals:
Syntax
iscsiadm -m discovery -t st -p IP_ADDR
Log in to target:
Syntax
iscsiadm -m node -T TARGET -l
View the multipath I/O configuration. The
multipathd
daemon sets up devices automatically based on the settings in themultipath.conf
file.Use the
multipath
command to show devices setup in a failover configuration with a priority group for each path, for example:Example
[root@rhel ~]# multipath -ll mpathbt (360014059ca317516a69465c883a29603) dm-1 LIO-ORG,TCMU device size=1.0G features='0' hwhandler='1 alua' wp=rw |-+- policy='queue-length 0' prio=50 status=active | `- 28:0:0:1 sde 8:64 active ready running `-+- policy='queue-length 0' prio=10 status=enabled `- 29:0:0:1 sdc 8:32 active ready running
The
multipath -ll
outputprio
value indicates the ALUA state, whereprio=50
indicates it is the path to the owning iSCSI gateway in the ALUA Active-Optimized state andprio=10
indicates it is an Active-non-Optimized path. Thestatus
field indicates which path is being used, whereactive
indicates the currently used path, andenabled
indicates the failover path, if theactive
fails.To match the device name, for example,
sde
in themultipath -ll
output, to the iSCSI gateway:Example
[root@rhel ~]# iscsiadm -m session -P 3
The
Persistent Portal
value is the IP address assigned to the iSCSI gateway listed in thegwcli
utility.
10.5.2. Configuring the iSCSI initiator for Red Hat Virtualization
Prerequisites
- Red Hat Virtualization 4.1
- Configured MPIO devices on all Red Hat Virtualization nodes
-
The
iscsi-initiator-utils-6.2.0.873-35
package or newer -
The
device-mapper-multipath-0.4.9-99
package or newer
Procedure
Configure multipath I/O.
Update the
/etc/multipath/conf.d/DEVICE_NAME.conf
file as follows:devices { device { vendor "LIO-ORG" product "TCMU device" hardware_handler "1 alua" path_grouping_policy "failover" path_selector "queue-length 0" failback 60 path_checker tur prio alua prio_args exclusive_pref_bit fast_io_fail_tmo 25 no_path_retry queue } }
Restart the
multipathd
service:[root@rhv ~]# systemctl reload multipathd
- Click the Storage resource tab to list the existing storage domains.
- Click the New Domain button to open the New Domain window.
- Enter the Name of the new storage domain.
- Use the Data Center drop-down menu to select an data center.
- Use the drop-down menus to select the Domain Function and the Storage Type. The storage domain types that are not compatible with the chosen domain function are not available.
- Select an active host in the Use Host field. If this is not the first data domain in a data center, you must select the data center’s SPM host.
The New Domain window automatically displays known targets with unused LUNs when iSCSI is selected as the storage type. If the target that you are adding storage from is not listed then you can use target discovery to find it, otherwise proceed to the next step.
- Click Discover Targets to enable target discovery options. When targets have been discovered and logged in to, the New Domain window automatically displays targets with LUNs unused by the environment. Note that LUNs external to the environment are also displayed. You can use the Discover Targets options to add LUNs on many targets, or multiple paths to the same LUNs.
- Enter the fully qualified domain name or IP address of the iSCSI host in the Address field.
-
Enter the port to connect to the host on when browsing for targets in the Port field. The default is
3260
. - If the Challenge Handshake Authentication Protocol (CHAP) is being used to secure the storage, select the User Authentication check box. Enter the CHAP user name and CHAP password.
- Click the Discover button.
Select the target to use from the discovery results and click the Login button. Alternatively, click the Login All to log in to all of the discovered targets.
ImportantIf more than one path access is required, ensure to discover and log in to the target through all the required paths. Modifying a storage domain to add additional paths is currently not supported.
- Click the + button next to the desired target. This will expand the entry and display all unused LUNs attached to the target.
- Select the check box for each LUN that you are using to create the storage domain.
Optionally, you can configure the advanced parameters.
- Click Advanced Parameters.
- Enter a percentage value into the Warning Low Space Indicator field. If the free space available on the storage domain is below this percentage, warning messages are displayed to the user and logged.
- Enter a GB value into the Critical Space Action Blocker field. If the free space available on the storage domain is below this value, error messages are displayed to the user and logged, and any new action that consumes space, even temporarily, will be blocked.
-
Select the Wipe After Delete check box to enable the
wipe after delete
option. You can edit this option after creating the domain, but doing so does not change thewipe after delete
property of disks that already exist. - Select the Discard After Delete check box to enable the discard after delete option. You can edit this option after creating the domain. This option is only available to block storage domains.
- Click OK to create the storage domain and close the window.
10.5.3. Configuring the iSCSI initiator for Microsoft Windows
Prerequisites
- Microsoft Windows Server 2016
Procedure
Install the iSCSI initiator and configure discovery and setup.
- Install the iSCSI initiator driver and MPIO tools.
- Launch the MPIO program, click the Discover Multi-Paths tab, check the Add support for iSCSI devices box, and click Add.
- Reboot the MPIO program.
- On the iSCSI Initiator Properties window, on the Discovery tab, add a target portal. Enter the IP address or DNS name and Port of the Ceph iSCSI gateway.
- On the Targets tab, select the target and click Connect.
- On the Connect To Target window, select the Enable multi-path option, and click the Advanced button.
Under the Connect using section, select the Microsoft ISCSI Intiator as the Local adapter from the drop-down box. Select the Windows client IP address as the Initiator IP from the drop-down box. Select a Target portal IP address. Select Enable CHAP login on and enter the Name and Target secret values from the Ceph iSCSI client credentials section, and click OK.
ImportantWindows Server 2016 does not accept a CHAP secret less than 12 bytes.
- Repeat the previous two steps for each target portal defined when setting up the iSCSI gateway before clicking on the Connecting tab.
- If the initiator name is different than the initiator name used during the initial setup, rename the initiator name. From iSCSI Initiator Properties window, on the Configuration tab, click the Change button to rename the initiator name.
Set up
multipath
I/O. In PowerShell, use thePDORemovePeriod
command to set the MPIO load balancing policy and thempclaim
command to set the load balancing policy. The iSCSI Initiator Tool configures the remaining options.NoteRed Hat recommends increasing the
PDORemovePeriod
option to 120 seconds from PowerShell. You might need to adjust this value based on the application. When all paths are down, and 120 seconds expires, the operating system starts failing I/O requests.Set-MPIOSetting -NewPDORemovePeriod 120
Set the failover policy
mpclaim.exe -l -m 1
Verify the failover policy
mpclaim -s -m MSDSM-wide Load Balance Policy: Fail Over Only
- Using the iSCSI Initiator tool, from the Targets tab click on the Devices… button:
- From the Devices window, select a disk and click the MPIO… button:
- The Device Details window displays the paths to each target portal. The Load Balancing Policy Fail Over Only must be selected.
View the
multipath
configuration from the PowerShell:mpclaim -s -d MPIO_DISK_ID
Replace MPIO_DISK_ID with the appropriate disk identifier.
NoteThere is one Active/Optimized path which is the path to the iSCSI gateway node that owns the LUN, and there is an Active/Unoptimized path for each other iSCSI gateway node.
Optionally, tune the settings. Consider using the following registry settings:
Windows Disk Timeout
Key
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk
Value
TimeOutValue = 65
Microsoft iSCSI Initiator Driver
Key
HKEY_LOCAL_MACHINE\\SYSTEM\CurrentControlSet\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\<Instance_Number>\Parameters
Values
LinkDownTime = 25 SRBTimeoutDelta = 15
10.5.4. Configuring the iSCSI initiator for VMware ESXi
Prerequisites
- See the iSCSI Gateway (IGW) section in the Customer Portal Knowledgebase article for supported VMware ESXi versions.
- Access to the VMware ESXi web interface.
-
Root access to VMware ESXi host console to execute the
esxcli
command.
Procedure
- Log into the VMware ESXi web interface.
-
Click on Actions
highlight Services click Enable SSH. Log into the VMware ESXi host console, and disable
HardwareAcceleratedMove
(XCOPY):> esxcli system settings advanced set --int-value 0 --option /DataMover/HardwareAcceleratedMove
- From the VMware ESXi web interface, on the Navigator pane, click Storage. Click on the Adapters tab. Highlight the adapter, and click on Configure iSCSI.
- Verify the initiator name in the Name & alias field.
If the initiator name is different than the initiator name used when creating the client during the initial setup using the
gwcli
utility, then change the initiator name. From the VMware ESXi host console, do the following steps.Get the adapter name for the iSCSI software:
> esxcli iscsi adapter list > Adapter Driver State UID Description > ------- --------- ------ ------------- ---------------------- > vmhba64 iscsi_vmk online iscsi.vmhba64 iSCSI Software Adapter
Set the initiator name:
Syntax
esxcli iscsi adapter set -A ADAPTOR_NAME -n INITIATOR_NAME
Example
> esxcli iscsi adapter set -A vmhba64 -n iqn.1994-05.com.redhat:rh8-client
- Verify the new initiator name from the VMware ESXi web interface. Click Storage in the Navigator pane. Click Software iSCSI. The new initiator name is in the Name & alias field, along with the Ceph Object Gateway node names.
Expand the CHAP authentication section. From the drop-down list, select Do not use CHAP unless required by target. Enter the CHAP Name and Secret credentials that were used in the initial setup. Verify the Mutual CHAP authentication section has Do not use CHAP selected.
ImportantThe usernames/passwords should not be the same for admin and mutual CHAP authentication.
-
The
username
/mutual_username
is 8-64 characters long, containing any alphanumeric in the range of [0-9
,a-z
,A-Z
] and.
,:
,@
,_
,-
. -
The
password
/mutual_password
is 12-16 characters long, containing any alphanumeric in the range of [0-9
,a-z
,A-Z
] and@
,-
,_
,/
.
WarningDue to a bug in the VMware host client, the CHAP settings are not used initially. On the Ceph iSCSI gateway node, the kernel logs include the following errors as an indication of this bug:
> kernel: CHAP user or password not set for Initiator ACL > kernel: Security negotiation failed. > kernel: iSCSI Login negotiation failed.
To work around this bug, configure the CHAP settings using the
esxcli
command. Theauthname
argument is the Name in the CHAP authentication section:Syntax
esxcli iscsi adapter auth chap set --direction=uni --authname=ISCSI_USER_NAME --secret=ISCSI_PASSWORD --level=discouraged -A ADAPTOR_NAME
-
The
- Expand Advanced settings section. Set the RecoveryTimeout value to 25.
In the Dynamic targets section, click on Add dynamic target. Under the Address field click to add an IP addresses for one of the Ceph iSCSI gateways. Only one IP address needs to be added. Finally, click the Save configuration button. Click on the Devices tab to see the RBD image.
NoteLUN is configured automatically, using the ALUA SATP and MRU PSP. Do not use other SATPs and PSPs. You can verify this by the
esxcli
command:Syntax
esxcli storage nmp path list -d eui.DEVICE_ID
Replace DEVICE_ID with the appropriate device identifier.
From the VMware ESXi host console, verify that multipathing is set up correctly.
List the devices:
Example
> esxcli storage nmp device list | grep iSCSI Device Display Name: LIO-ORG iSCSI Disk (naa.6001405f8d087846e7b4f0e9e3acd44b) Device Display Name: LIO-ORG iSCSI Disk (naa.6001405057360ba9b4c434daa3c6770c)
Get the multipath information for the Ceph iSCSI disk from the previous step:
Example
> esxcli storage nmp path list -d naa.6001405f8d087846e7b4f0e9e3acd44b iqn.2005-03.com.ceph:esx1-00023d000001,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,t,1-naa.6001405f8d087846e7b4f0e9e3acd44b Runtime Name: vmhba64:C0:T0:L0 Device: naa.6001405f8d087846e7b4f0e9e3acd44b Device Display Name: LIO-ORG iSCSI Disk (naa.6001405f8d087846e7b4f0e9e3acd44b) Group State: active Array Priority: 0 Storage Array Type Path Config: {TPG_id=1,TPG_state=AO,RTP_id=1,RTP_health=UP} Path Selection Policy Path Config: {current path; rank: 0} iqn.2005-03.com.ceph:esx1-00023d000002,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,t,2-naa.6001405f8d087846e7b4f0e9e3acd44b Runtime Name: vmhba64:C1:T0:L0 Device: naa.6001405f8d087846e7b4f0e9e3acd44b Device Display Name: LIO-ORG iSCSI Disk (naa.6001405f8d087846e7b4f0e9e3acd44b) Group State: active unoptimized Array Priority: 0 Storage Array Type Path Config: {TPG_id=2,TPG_state=ANO,RTP_id=2,RTP_health=UP} Path Selection Policy Path Config: {non-current path; rank: 0}
From the example output, each path has an iSCSI or SCSI name with the following parts:
Initiator name =
iqn.2005-03.com.ceph:esx1
ISID =00023d000002
Target name =iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw
Target port group =2
Device id =naa.6001405f8d087846e7b4f0e9e3acd44b
The
Group State
value ofactive
indicates this is the Active-Optimized path to the iSCSI gateway. Thegwcli
command lists theactive
as the iSCSI gateway owner. The rest of the paths have theGroup State
value ofunoptimized
and are the failover path, if theactive
path goes into adead
state.To match all paths to their respective iSCSI gateways:
Example
> esxcli iscsi session connection list vmhba64,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,00023d000001,0 Adapter: vmhba64 Target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw ISID: 00023d000001 CID: 0 DataDigest: NONE HeaderDigest: NONE IFMarker: false IFMarkerInterval: 0 MaxRecvDataSegmentLength: 131072 MaxTransmitDataSegmentLength: 262144 OFMarker: false OFMarkerInterval: 0 ConnectionAddress: 10.172.19.21 RemoteAddress: 10.172.19.21 LocalAddress: 10.172.19.11 SessionCreateTime: 08/16/18 04:20:06 ConnectionCreateTime: 08/16/18 04:20:06 ConnectionStartTime: 08/16/18 04:30:45 State: logged_in vmhba64,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,00023d000002,0 Adapter: vmhba64 Target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw ISID: 00023d000002 CID: 0 DataDigest: NONE HeaderDigest: NONE IFMarker: false IFMarkerInterval: 0 MaxRecvDataSegmentLength: 131072 MaxTransmitDataSegmentLength: 262144 OFMarker: false OFMarkerInterval: 0 ConnectionAddress: 10.172.19.22 RemoteAddress: 10.172.19.22 LocalAddress: 10.172.19.12 SessionCreateTime: 08/16/18 04:20:06 ConnectionCreateTime: 08/16/18 04:20:06 ConnectionStartTime: 08/16/18 04:30:41 State: logged_in
Match the path name with the
ISID
value, and theRemoteAddress
value is the IP address of the owning iSCSI gateway.
- From the VMware ESXi web interface, click on the Devices tab to see the iSCSI disk.
Click on New datastore to start the wizard.
- Provide a name for the new datastore, and click Next.
- Select Use full disk, and click Next.
- Click Finish. A warning message appears about erasing the disk. Click Yes to proceed, and create the new datastore.
- The new datastore will appear on the Datastores tab.
You can check disk usage by selecting the datastore name. You can also check disk usage from Ceph by running the following command:
Syntax
rbd du --pool POOL_NAME
Example
[root@rbd-client ~]# rbd du --pool rbdpool
10.6. Adding more iSCSI gateways
As a storage administrator, you can expand the initial two iSCSI gateways to four iSCSI gateways by using the gwcli
command-line tool or the Red Hat Ceph Storage Dashboard. Adding more iSCSI gateways provides you more flexibility when using load-balancing and failover options, along with providing more redundancy.
10.6.1. Prerequisites
- A running Red Hat Ceph Storage 5 cluster
- Spare nodes or existing OSD nodes
-
root
permissions
10.6.2. Using gwcli
to add more iSCSI gateways
You can use the gwcli
command-line tool to add more iSCSI gateways. This procedure expands the default of two iSCSI gateways to four iSCSI gateways.
Prerequisites
- Red Hat Enterprise Linux 8.7 or later.
- A running Red Hat Ceph Storage cluster.
-
Having
root
user access to the new nodes or OSD nodes.
Procedure
On the new iSCSI gateway hosts, enable the Red Hat Ceph Storage Tools repository:
Example
[root@iscsigw ~]# subscription-manager repos --enable=rhceph-5-tools-for-rhel-8-x86_64-rpms
Install the
ceph-iscsi
, andtcmu-runner
packages:Example
[root@iscsigw ~]# dnf install ceph-iscsi tcmu-runner
Create the specification file:
Syntax
cat iscsi-gateway.yaml service_type: iscsi service_id: SERVICE_ID service_name: SERVICE_NAME placement: hosts: - HOSTNAME_1 - HOSTNAME_2 - HOSTNAME_3 - HOSTNAME_4 spec: pool: POOL_NAME trusted_ip_list: IP_ADDRESS_1, IP_ADDRESS_2, IP_ADDRESS_3, IP_ADDRESS_4
Example
[root@iscsigw ~]# cat iscsi-gateway.yaml service_type: iscsi service_id: iscsi service_name: iscsi.iscsi placement: hosts: - host01 - host02 - host03 - host04 spec: pool: rbd trusted_ip_list: 192.168.0.10,192.168.0.13,192.168.0.198,192.168.0.50,192.168.0.51
Optional: Add proper rules in firewall for the newly added node/nodes:
Example
[root@host01 ~]# firewall-cmd --permanent --add-port=5000/tcp ; firewall-cmd --permanent --add-port=3260/tcp ; firewall-cmd --reload
Notecephadm
might open the ports on its own.Mount the YAML file under a directory in the container:
Example
[root@host01 ~]# cephadm shell --mount iscsi-gateway.yaml:/var/lib/ceph/iscsi-gateway.yaml
Navigate to the directory:
Example
[ceph: root@host01 /]# cd /var/lib/ceph
Deploy the Ceph iSCSI service:
Syntax
ceph orch apply -i FILE_NAME.yaml
Example
[ceph: root@host01 ceph]# ceph orch apply -i iscsi-gateway.yaml
Optional: Deploy the Ceph iSCSI service using the placement specification:
Syntax
ceph orch apply iscsi POOL_NAME --placement="HOSTNAME_1,HOSTNAME_2,HOSTNAME_3,HOSTNAME_4" --trusted_ip_list="IP_ADDRESS_1,IP_ADDRESS_2,IP_ADDRESS_3,IP_ADDRESS_4" admin admin
Example
[ceph: root@host01 ceph]# ceph orch apply iscsi iscsipool --placement="ceph-amk5-m0g9z7-node1-installer,ceph-amk5-m0g9z7-node4" --trusted_ip_list="10.0.210.209,10.0.210.153,192.168.0.50,192.168.0.51" admin admin
Verify the installation:
Example
[ceph: root@host01 /]# ceph orch ls --service_type=iscsi NAME PORTS RUNNING REFRESHED AGE PLACEMENT iscsi.foo ?:5000 3/3 10m ago 75s host01;host02;host03;host04
From the
ceph orch ps
command, get the hostname on which iSCSI is installed:Example
[ceph: root@host01 /]# ceph orch ps --daemon_type=iscsi NAME HOST PORTS STATUS REFRESHED AGE MEM USE MEM LIM VERSION IMAGE ID CONTAINER ID iscsi.foo.host02 host02 *:9095 running (2h) 8m ago 2h 85.3M - 2.22.2 ac25aac5d567 ad8c7593d7c0
Enter the container:
Example
[ceph: root@host01 /]# cephadm enter --name iscsi.foo.host02.tetras
Add the gateway using the gwcli from the iSCSI container:
Example
[root@host02 /]# gwcli /iscsi-target...get1/gateways> goto gateways /iscsi-target...get1/gateways> create host03 192.168.0.50 Adding gateway, sync'ing 1 disk(s) and 1 client(s) ok /iscsi-target...get1/gateways> create host04 192.168.0.51 Adding gateway, sync'ing 1 disk(s) and 1 client(s) ok /iscsi-target...get1/gateways> ls o- gateways .................................................................................................. [Up: 3/3, Portals: 3] o- host01 .................................................................................. [192.168.0.10 (UP)] o- host02.................................................................................. [192.168.0.13 (UP)]s o- host03.................................................................................... [192.168.0.50 (UP)] o- host04.................................................................................... [192.168.0.51 (UP)] /iscsi-target...get1/gateways>
10.7. Verifying that the initiator is connected to the iSCSI target
After installing the iSCSI gateway and configuring the iSCSI target and an initiator, verify that the initiator is properly connected to the iSCSI target.
Prerequisites
- Installation of the Ceph iSCSI gateway software.
- Configured the iSCSI target.
- Configured the iSCSI initiator.
Procedure
Start the iSCSI gateway command-line interface:
[root@iscsigw ~]# gwcli
Verify that the initiator is connected the iSCSI target:
/> goto hosts /iscsi-target...csi-igw/hosts> ls o- hosts .............................. [Hosts: 1: Auth: None] o- iqn.1994-05.com.redhat:rh7-client [LOGGED-IN, Auth: None, Disks: 0(0.00Y)]
The initiator status is
LOGGED-IN
if it is connected.Verify that LUNs are balanced across iSCSI gateways:
/> goto hosts /iscsi-target...csi-igw/hosts> ls o- hosts ................................. [Hosts: 2: Auth: None] o- iqn.2005-03.com.ceph:esx ............ [Auth: None, Disks: 4(310G)] | o- lun 0 ............................. [rbd.disk_1(100G), Owner: ceph-gw-1] | o- lun 1 ............................. [rbd.disk_2(10G), Owner: ceph-gw-2]
When creating a disk, the disk is assigned an iSCSI gateway as its
Owner
based on what gateways have the lowest number of mapped LUNs. If this number is balanced, gateways are assigned based on a round robin allocation. Currently, the balancing of LUNs is not dynamic and cannot be selected by the user.When the initiator is logged into the target, and the
multipath
layer is in a optimized state, the initiator’s operating systemmultipath
utilities report the path to theOwner
gateway as being in ALUA Active-Optimized (AO) state. Themultipath
utilities report the other paths as being in the ALUA Active-non-Optimized (ANO) state.If the AO path fails, one of the other iSCSI gateways is used. The ordering for the failover gateway depends on the initiator’s
multipath
layer, where normally, the order is based on which path was discovered first.
10.8. Monitoring the iSCSI gateways
Red Hat Ceph Storage cluster now incorporates a generic metric gathering framework within the OSDs and MGRs to provide built-in monitoring. The metrics are generated within the Red Hat Ceph Storage cluster and there is no need to access client nodes to scrape metrics.
To monitor the performance of RBD images, Ceph has a built-in MGR Prometheus exporter module to translate individual RADOS object metrics into aggregated RBD image metrics for Input/Output(I/O) operations per second, throughput, and latency. The Ceph iSCSI gateway also provides a Prometheus exporter for Linux-IO (LIO) level performance metrics, supporting monitoring and visualization tools like Grafana. These metrics include the information about defined Target Portal Groups (TPGs) and mapped Logical Unit Numbers (LUNs), per LUN state and the number of Input Output operations per second (IOPS), read bytes and write bytes per LUN per client. By default, the Prometheus exporter is enabled.
You can change the default settings by using the following options in the iscsi-gateway.cfg
:
Example
[config] prometheus_exporter = True prometheus_port = 9287 prometheus_host = xx.xx.xx.xxx
The gwtop
tool used for Ceph iSCSI gateway environments to monitor performance of exported Ceph block device (RBD) images is deprecated.
Additional Resources
- See the Management of iSCSI functions using the Ceph dashboard section in the Red Hat Ceph Storage Dashboard Guide for more details.
10.9. Removing the iSCSI configuration
To remove the iSCSI configuration, use the gwcli
utility to remove hosts and disks.
Prerequisites
Disconnect all iSCSI initiators:
Red Hat Enterprise Linux initiators:
Syntax
iscsiadm -m node -T TARGET_NAME --logout
Replace
TARGET_NAME
with the configured iSCSI target name, for example:Example
# iscsiadm -m node -T iqn.2003-01.com.redhat.iscsi-gw:ceph-igw --logout Logging out of session [sid: 1, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.21,3260] Logging out of session [sid: 2, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.22,3260] Logout of [sid: 1, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.21,3260] successful. Logout of [sid: 2, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.22,3260] successful.
Windows initiators:
See the Microsoft documentation for more details.
VMware ESXi initiators:
See the VMware documentation for more details.
Procedure
Run the iSCSI gateway command line utility:
[root@iscsigw ~]# gwcli
Remove the hosts:
Syntax
/> cd /iscsi-target/iqn.2003-01.com.redhat.iscsi-gw:$TARGET_NAME/hosts /> /iscsi-target...TARGET_NAME/hosts> delete CLIENT_NAME
Replace
TARGET_NAME
with the configured iSCSI target name, and replaceCLIENT_NAME
with iSCSI initiator name, for example:Example
/> cd /iscsi-target/iqn.2003-01.com.redhat.iscsi-gw:ceph-igw/hosts /> /iscsi-target...eph-igw/hosts> delete iqn.1994-05.com.redhat:rh7-client
Remove the disks:
Syntax
/> cd /disks/ /disks> delete POOL_NAME.IMAGE_NAME
Replace
POOL_NAME
with the name of the pool and theIMAGE_NAME
with the name of the image, for example:Example
/> cd /disks/ /disks> delete rbd.disk_1
10.10. Additional Resources
- For details on managing iSCSI gateway using the Red Hat Ceph Storage Dashboard, see the iSCSI functions section in the Dashboard Guide for Red Hat Ceph Storage 5.