Chapter 8. GFS2 file systems in a cluster
Use the following administrative procedures to configure GFS2 file systems in a Red Hat high availability cluster.
8.1. Configuring a GFS2 file system in a cluster
You can set up a Pacemaker cluster that includes GFS2 file systems with the following procedure. In this example, you create three GFS2 file systems on three logical volumes in a two-node cluster.
Prerequisites
- Install and start the cluster software on both cluster nodes and create a basic two-node cluster.
- Configure fencing for the cluster.
For information about creating a Pacemaker cluster and configuring fencing for the cluster, see Creating a Red Hat High-Availability cluster with Pacemaker.
Procedure
On both nodes in the cluster, enable the repository for Resilient Storage that corresponds to your system architecture. For example, to enable the Resilient Storage repository for an x86_64 system, you can enter the following
subscription-managercommand:# subscription-manager repos --enable=rhel-8-for-x86_64-resilientstorage-rpmsNote that the Resilient Storage repository is a superset of the High Availability repository. If you enable the Resilient Storage repository you do not also need to enable the High Availability repository.
On both nodes of the cluster, install the
lvm2-lockd,gfs2-utils, anddlmpackages. To support these packages, you must be subscribed to the AppStream channel and the Resilient Storage channel.# yum install lvm2-lockd gfs2-utils dlmOn both nodes of the cluster, set the
use_lvmlockdconfiguration option in the/etc/lvm/lvm.conffile touse_lvmlockd=1.... use_lvmlockd = 1 ...
Set the global Pacemaker parameter
no-quorum-policytofreeze.NoteBy default, the value of
no-quorum-policyis set tostop, indicating that once quorum is lost, all the resources on the remaining partition will immediately be stopped. Typically this default is the safest and most optimal option, but unlike most resources, GFS2 requires quorum to function. When quorum is lost both the applications using the GFS2 mounts and the GFS2 mount itself cannot be correctly stopped. Any attempts to stop these resources without quorum will fail which will ultimately result in the entire cluster being fenced every time quorum is lost.To address this situation, set
no-quorum-policytofreezewhen GFS2 is in use. This means that when quorum is lost, the remaining partition will do nothing until quorum is regained.[root@z1 ~]# pcs property set no-quorum-policy=freezeSet up a
dlmresource. This is a required dependency for configuring a GFS2 file system in a cluster. This example creates thedlmresource as part of a resource group namedlocking.[root@z1 ~]# pcs resource create dlm --group locking ocf:pacemaker:controld op monitor interval=30s on-fail=fenceClone the
lockingresource group so that the resource group can be active on both nodes of the cluster.[root@z1 ~]# pcs resource clone locking interleave=trueSet up an
lvmlockdresource as part of thelockingresource group.[root@z1 ~]# pcs resource create lvmlockd --group locking ocf:heartbeat:lvmlockd op monitor interval=30s on-fail=fenceCheck the status of the cluster to ensure that the
lockingresource group has started on both nodes of the cluster.[root@z1 ~]# pcs status --full Cluster name: my_cluster [...] Online: [ z1.example.com (1) z2.example.com (2) ] Full list of resources: smoke-apc (stonith:fence_apc): Started z1.example.com Clone Set: locking-clone [locking] Resource Group: locking:0 dlm (ocf::pacemaker:controld): Started z1.example.com lvmlockd (ocf::heartbeat:lvmlockd): Started z1.example.com Resource Group: locking:1 dlm (ocf::pacemaker:controld): Started z2.example.com lvmlockd (ocf::heartbeat:lvmlockd): Started z2.example.com Started: [ z1.example.com z2.example.com ]On one node of the cluster, create two shared volume groups. One volume group will contain two GFS2 file systems, and the other volume group will contain one GFS2 file system.
NoteIf your LVM volume group contains one or more physical volumes that reside on remote block storage, such as an iSCSI target, Red Hat recommends that you ensure that the service starts before Pacemaker starts. For information about configuring startup order for a remote physical volume used by a Pacemaker cluster, see Configuring startup order for resource dependencies not managed by Pacemaker.
The following command creates the shared volume group
shared_vg1on/dev/vdb.[root@z1 ~]# vgcreate --shared shared_vg1 /dev/vdb Physical volume "/dev/vdb" successfully created. Volume group "shared_vg1" successfully created VG shared_vg1 starting dlm lockspace Starting locking. Waiting until locks are ready...The following command creates the shared volume group
shared_vg2on/dev/vdc.[root@z1 ~]# vgcreate --shared shared_vg2 /dev/vdc Physical volume "/dev/vdc" successfully created. Volume group "shared_vg2" successfully created VG shared_vg2 starting dlm lockspace Starting locking. Waiting until locks are ready...On the second node in the cluster:
(RHEL 8.5 and later) If you have enabled the use of a devices file by setting
use_devicesfile = 1in thelvm.conffile, add the shared devices to the devices file. By default, the use of a devices file is not enabled.[root@z2 ~]# lvmdevices --adddev /dev/vdb [root@z2 ~]# lvmdevices --adddev /dev/vdc
Start the lock manager for each of the shared volume groups.
[root@z2 ~]# vgchange --lockstart shared_vg1 VG shared_vg1 starting dlm lockspace Starting locking. Waiting until locks are ready... [root@z2 ~]# vgchange --lockstart shared_vg2 VG shared_vg2 starting dlm lockspace Starting locking. Waiting until locks are ready...
On one node in the cluster, create the shared logical volumes and format the volumes with a GFS2 file system. One journal is required for each node that mounts the file system. Ensure that you create enough journals for each of the nodes in your cluster. The format of the lock table name is ClusterName:FSName where ClusterName is the name of the cluster for which the GFS2 file system is being created and FSName is the file system name, which must be unique for all
lock_dlmfile systems over the cluster.[root@z1 ~]# lvcreate --activate sy -L5G -n shared_lv1 shared_vg1 Logical volume "shared_lv1" created. [root@z1 ~]# lvcreate --activate sy -L5G -n shared_lv2 shared_vg1 Logical volume "shared_lv2" created. [root@z1 ~]# lvcreate --activate sy -L5G -n shared_lv1 shared_vg2 Logical volume "shared_lv1" created. [root@z1 ~]# mkfs.gfs2 -j2 -p lock_dlm -t my_cluster:gfs2-demo1 /dev/shared_vg1/shared_lv1 [root@z1 ~]# mkfs.gfs2 -j2 -p lock_dlm -t my_cluster:gfs2-demo2 /dev/shared_vg1/shared_lv2 [root@z1 ~]# mkfs.gfs2 -j2 -p lock_dlm -t my_cluster:gfs2-demo3 /dev/shared_vg2/shared_lv1
Create an
LVM-activateresource for each logical volume to automatically activate that logical volume on all nodes.Create an
LVM-activateresource namedsharedlv1for the logical volumeshared_lv1in volume groupshared_vg1. This command also creates the resource groupshared_vg1that includes the resource. In this example, the resource group has the same name as the shared volume group that includes the logical volume.[root@z1 ~]# pcs resource create sharedlv1 --group shared_vg1 ocf:heartbeat:LVM-activate lvname=shared_lv1 vgname=shared_vg1 activation_mode=shared vg_access_mode=lvmlockdCreate an
LVM-activateresource namedsharedlv2for the logical volumeshared_lv2in volume groupshared_vg1. This resource will also be part of the resource groupshared_vg1.[root@z1 ~]# pcs resource create sharedlv2 --group shared_vg1 ocf:heartbeat:LVM-activate lvname=shared_lv2 vgname=shared_vg1 activation_mode=shared vg_access_mode=lvmlockdCreate an
LVM-activateresource namedsharedlv3for the logical volumeshared_lv1in volume groupshared_vg2. This command also creates the resource groupshared_vg2that includes the resource.[root@z1 ~]# pcs resource create sharedlv3 --group shared_vg2 ocf:heartbeat:LVM-activate lvname=shared_lv1 vgname=shared_vg2 activation_mode=shared vg_access_mode=lvmlockd
Clone the two new resource groups.
[root@z1 ~]# pcs resource clone shared_vg1 interleave=true [root@z1 ~]# pcs resource clone shared_vg2 interleave=true
Configure ordering constraints to ensure that the
lockingresource group that includes thedlmandlvmlockdresources starts first.[root@z1 ~]# pcs constraint order start locking-clone then shared_vg1-clone Adding locking-clone shared_vg1-clone (kind: Mandatory) (Options: first-action=start then-action=start) [root@z1 ~]# pcs constraint order start locking-clone then shared_vg2-clone Adding locking-clone shared_vg2-clone (kind: Mandatory) (Options: first-action=start then-action=start)
Configure colocation constraints to ensure that the
vg1andvg2resource groups start on the same node as thelockingresource group.[root@z1 ~]# pcs constraint colocation add shared_vg1-clone with locking-clone [root@z1 ~]# pcs constraint colocation add shared_vg2-clone with locking-clone
On both nodes in the cluster, verify that the logical volumes are active. There may be a delay of a few seconds.
[root@z1 ~]# lvs LV VG Attr LSize shared_lv1 shared_vg1 -wi-a----- 5.00g shared_lv2 shared_vg1 -wi-a----- 5.00g shared_lv1 shared_vg2 -wi-a----- 5.00g [root@z2 ~]# lvs LV VG Attr LSize shared_lv1 shared_vg1 -wi-a----- 5.00g shared_lv2 shared_vg1 -wi-a----- 5.00g shared_lv1 shared_vg2 -wi-a----- 5.00g
Create a file system resource to automatically mount each GFS2 file system on all nodes.
You should not add the file system to the
/etc/fstabfile because it will be managed as a Pacemaker cluster resource. Mount options can be specified as part of the resource configuration withoptions=options. Run thepcs resource describe Filesystemcommand to display the full configuration options.The following commands create the file system resources. These commands add each resource to the resource group that includes the logical volume resource for that file system.
[root@z1 ~]# pcs resource create sharedfs1 --group shared_vg1 ocf:heartbeat:Filesystem device="/dev/shared_vg1/shared_lv1" directory="/mnt/gfs1" fstype="gfs2" options=noatime op monitor interval=10s on-fail=fence [root@z1 ~]# pcs resource create sharedfs2 --group shared_vg1 ocf:heartbeat:Filesystem device="/dev/shared_vg1/shared_lv2" directory="/mnt/gfs2" fstype="gfs2" options=noatime op monitor interval=10s on-fail=fence [root@z1 ~]# pcs resource create sharedfs3 --group shared_vg2 ocf:heartbeat:Filesystem device="/dev/shared_vg2/shared_lv1" directory="/mnt/gfs3" fstype="gfs2" options=noatime op monitor interval=10s on-fail=fence
Verification steps
Verify that the GFS2 file systems are mounted on both nodes of the cluster.
[root@z1 ~]# mount | grep gfs2 /dev/mapper/shared_vg1-shared_lv1 on /mnt/gfs1 type gfs2 (rw,noatime,seclabel) /dev/mapper/shared_vg1-shared_lv2 on /mnt/gfs2 type gfs2 (rw,noatime,seclabel) /dev/mapper/shared_vg2-shared_lv1 on /mnt/gfs3 type gfs2 (rw,noatime,seclabel) [root@z2 ~]# mount | grep gfs2 /dev/mapper/shared_vg1-shared_lv1 on /mnt/gfs1 type gfs2 (rw,noatime,seclabel) /dev/mapper/shared_vg1-shared_lv2 on /mnt/gfs2 type gfs2 (rw,noatime,seclabel) /dev/mapper/shared_vg2-shared_lv1 on /mnt/gfs3 type gfs2 (rw,noatime,seclabel)
Check the status of the cluster.
[root@z1 ~]# pcs status --full Cluster name: my_cluster [...] Full list of resources: smoke-apc (stonith:fence_apc): Started z1.example.com Clone Set: locking-clone [locking] Resource Group: locking:0 dlm (ocf::pacemaker:controld): Started z2.example.com lvmlockd (ocf::heartbeat:lvmlockd): Started z2.example.com Resource Group: locking:1 dlm (ocf::pacemaker:controld): Started z1.example.com lvmlockd (ocf::heartbeat:lvmlockd): Started z1.example.com Started: [ z1.example.com z2.example.com ] Clone Set: shared_vg1-clone [shared_vg1] Resource Group: shared_vg1:0 sharedlv1 (ocf::heartbeat:LVM-activate): Started z2.example.com sharedlv2 (ocf::heartbeat:LVM-activate): Started z2.example.com sharedfs1 (ocf::heartbeat:Filesystem): Started z2.example.com sharedfs2 (ocf::heartbeat:Filesystem): Started z2.example.com Resource Group: shared_vg1:1 sharedlv1 (ocf::heartbeat:LVM-activate): Started z1.example.com sharedlv2 (ocf::heartbeat:LVM-activate): Started z1.example.com sharedfs1 (ocf::heartbeat:Filesystem): Started z1.example.com sharedfs2 (ocf::heartbeat:Filesystem): Started z1.example.com Started: [ z1.example.com z2.example.com ] Clone Set: shared_vg2-clone [shared_vg2] Resource Group: shared_vg2:0 sharedlv3 (ocf::heartbeat:LVM-activate): Started z2.example.com sharedfs3 (ocf::heartbeat:Filesystem): Started z2.example.com Resource Group: shared_vg2:1 sharedlv3 (ocf::heartbeat:LVM-activate): Started z1.example.com sharedfs3 (ocf::heartbeat:Filesystem): Started z1.example.com Started: [ z1.example.com z2.example.com ] ...
Additional resources
- Configuring GFS2 file systems
- Configuring a Red Hat High Availability cluster on Microsoft Azure
- Configuring a Red Hat High Availability cluster on AWS
- Configuring a Red Hat High Availability Cluster on Google Cloud Platform
- Configuring shared block storage for a Red Hat High Availability cluster on Alibaba Cloud
8.2. Configuring an encrypted GFS2 file system in a cluster
(RHEL 8.4 and later) You can create a Pacemaker cluster that includes a LUKS encrypted GFS2 file system with the following procedure. In this example, you create one GFS2 file systems on a logical volume and encrypt the file system. Encrypted GFS2 file systems are supported using the crypt resource agent, which provides support for LUKS encryption.
There are three parts to this procedure:
- Configuring a shared logical volume in a Pacemaker cluster
-
Encrypting the logical volume and creating a
cryptresource - Formatting the encrypted logical volume with a GFS2 file system and creating a file system resource for the cluster
8.2.2. Encrypt the logical volume and create a crypt resource
Prerequisites
- You have configured a shared logical volume in a Pacemaker cluster.
Procedure
On one node in the cluster, create a new file that will contain the crypt key and set the permissions on the file so that it is readable only by root.
[root@z1 ~]# touch /etc/crypt_keyfile [root@z1 ~]# chmod 600 /etc/crypt_keyfile
Create the crypt key.
[root@z1 ~]# dd if=/dev/urandom bs=4K count=1 of=/etc/crypt_keyfile 1+0 records in 1+0 records out 4096 bytes (4.1 kB, 4.0 KiB) copied, 0.000306202 s, 13.4 MB/s [root@z1 ~]# scp /etc/crypt_keyfile root@z2.example.com:/etc/
Distribute the crypt keyfile to the other nodes in the cluster, using the
-pparameter to preserve the permissions you set.[root@z1 ~]# scp -p /etc/crypt_keyfile root@z2.example.com:/etc/Create the encrypted device on the LVM volume where you will configure the encrypted GFS2 file system.
[root@z1 ~]# cryptsetup luksFormat /dev/shared_vg1/shared_lv1 --type luks2 --key-file=/etc/crypt_keyfile WARNING! ======== This will overwrite data on /dev/shared_vg1/shared_lv1 irrevocably. Are you sure? (Type 'yes' in capital letters): YESCreate the crypt resource as part of the
shared_vg1volume group.[root@z1 ~]# pcs resource create crypt --group shared_vg1 ocf:heartbeat:crypt crypt_dev="luks_lv1" crypt_type=luks2 key_file=/etc/crypt_keyfile encrypted_dev="/dev/shared_vg1/shared_lv1"
Verification steps
Ensure that the crypt resource has created the crypt device, which in this example is /dev/mapper/luks_lv1.
[root@z1 ~]# ls -l /dev/mapper/
...
lrwxrwxrwx 1 root root 7 Mar 4 09:52 luks_lv1 -> ../dm-3
...8.2.3. Format the encrypted logical volume with a GFS2 file system and create a file system resource for the cluster
Prerequisites
- You have encrypted the logical volume and created a crypt resource.
Procedure
On one node in the cluster, format the volume with a GFS2 file system. One journal is required for each node that mounts the file system. Ensure that you create enough journals for each of the nodes in your cluster. The format of the lock table name is ClusterName:FSName where ClusterName is the name of the cluster for which the GFS2 file system is being created and FSName is the file system name, which must be unique for all
lock_dlmfile systems over the cluster.[root@z1 ~]# mkfs.gfs2 -j3 -p lock_dlm -t my_cluster:gfs2-demo1 /dev/mapper/luks_lv1 /dev/mapper/luks_lv1 is a symbolic link to /dev/dm-3 This will destroy any data on /dev/dm-3 Are you sure you want to proceed? [y/n] y Discarding device contents (may take a while on large devices): Done Adding journals: Done Building resource groups: Done Creating quota file: Done Writing superblock and syncing: Done Device: /dev/mapper/luks_lv1 Block size: 4096 Device size: 4.98 GB (1306624 blocks) Filesystem size: 4.98 GB (1306622 blocks) Journals: 3 Journal size: 16MB Resource groups: 23 Locking protocol: "lock_dlm" Lock table: "my_cluster:gfs2-demo1" UUID: de263f7b-0f12-4d02-bbb2-56642fade293Create a file system resource to automatically mount the GFS2 file system on all nodes.
Do not add the file system to the
/etc/fstabfile because it will be managed as a Pacemaker cluster resource. Mount options can be specified as part of the resource configuration withoptions=options. Run thepcs resource describe Filesystemcommand for full configuration options.The following command creates the file system resource. This command adds the resource to the resource group that includes the logical volume resource for that file system.
[root@z1 ~]# pcs resource create sharedfs1 --group shared_vg1 ocf:heartbeat:Filesystem device="/dev/mapper/luks_lv1" directory="/mnt/gfs1" fstype="gfs2" options=noatime op monitor interval=10s on-fail=fence
Verification steps
Verify that the GFS2 file system is mounted on both nodes of the cluster.
[root@z1 ~]# mount | grep gfs2 /dev/mapper/luks_lv1 on /mnt/gfs1 type gfs2 (rw,noatime,seclabel) [root@z2 ~]# mount | grep gfs2 /dev/mapper/luks_lv1 on /mnt/gfs1 type gfs2 (rw,noatime,seclabel)
Check the status of the cluster.
[root@z1 ~]# pcs status --full Cluster name: my_cluster [...] Full list of resources: smoke-apc (stonith:fence_apc): Started z1.example.com Clone Set: locking-clone [locking] Resource Group: locking:0 dlm (ocf::pacemaker:controld): Started z2.example.com lvmlockd (ocf::heartbeat:lvmlockd): Started z2.example.com Resource Group: locking:1 dlm (ocf::pacemaker:controld): Started z1.example.com lvmlockd (ocf::heartbeat:lvmlockd): Started z1.example.com Started: [ z1.example.com z2.example.com ] Clone Set: shared_vg1-clone [shared_vg1] Resource Group: shared_vg1:0 sharedlv1 (ocf::heartbeat:LVM-activate): Started z2.example.com crypt (ocf::heartbeat:crypt) Started z2.example.com sharedfs1 (ocf::heartbeat:Filesystem): Started z2.example.com Resource Group: shared_vg1:1 sharedlv1 (ocf::heartbeat:LVM-activate): Started z1.example.com crypt (ocf::heartbeat:crypt) Started z1.example.com sharedfs1 (ocf::heartbeat:Filesystem): Started z1.example.com Started: [z1.example.com z2.example.com ] ...
Additional resources
8.3. Migrating a GFS2 file system from RHEL7 to RHEL8
You can use your existing Red Hat Enterprise 7 logical volumes when configuring a RHEL 8 cluster that includes GFS2 file systems.
In Red Hat Enterprise Linux 8, LVM uses the LVM lock daemon lvmlockd instead of clvmd for managing shared storage devices in an active/active cluster. This requires that you configure the logical volumes that your active/active cluster will require as shared logical volumes. Additionally, this requires that you use the LVM-activate resource to manage an LVM volume and that you use the lvmlockd resource agent to manage the lvmlockd daemon. See Configuring a GFS2 file system in a cluster for a full procedure for configuring a Pacemaker cluster that includes GFS2 file systems using shared logical volumes.
To use your existing Red Hat Enterprise Linux 7 logical volumes when configuring a RHEL8 cluster that includes GFS2 file systems, perform the following procedure from the RHEL8 cluster. In this example, the clustered RHEL 7 logical volume is part of the volume group upgrade_gfs_vg.
The RHEL8 cluster must have the same name as the RHEL7 cluster that includes the GFS2 file system in order for the existing file system to be valid.
Procedure
- Ensure that the logical volumes containing the GFS2 file systems are currently inactive. This procedure is safe only if all nodes have stopped using the volume group.
From one node in the cluster, forcibly change the volume group to be local.
[root@rhel8-01 ~]# vgchange --lock-type none --lock-opt force upgrade_gfs_vg Forcibly change VG lock type to none? [y/n]: y Volume group "upgrade_gfs_vg" successfully changedFrom one node in the cluster, change the local volume group to a shared volume group
[root@rhel8-01 ~]# vgchange --lock-type dlm upgrade_gfs_vg Volume group "upgrade_gfs_vg" successfully changedOn each node in the cluster, start locking for the volume group.
[root@rhel8-01 ~]# vgchange --lockstart upgrade_gfs_vg VG upgrade_gfs_vg starting dlm lockspace Starting locking. Waiting until locks are ready... [root@rhel8-02 ~]# vgchange --lockstart upgrade_gfs_vg VG upgrade_gfs_vg starting dlm lockspace Starting locking. Waiting until locks are ready...
After performing this procedure, you can create an LVM-activate resource for each logical volume.
