How can I switch from HA-LVM tagging method to CLVM method on Red Hat Enterprise Linux 6?

Solution Unverified - Updated 6 Aug 2024

Environment

Red Hat Enterprise Linux Server 6 (with the High Availability and Resilient Storage Add Ons)
2 or more nodes in a Red Hat Enterprise Linux 6 cluster
- rgmanager to manage cluster resources and service groups
  - At least one service is configured using HA-LVM tagging variant.

Issue

We will proceed to change the current configuration from HA-LVM tagging variant to CLVM variant. How can we do that?

Resolution

To disable a previously configured HA-LVM tagging variant configuration:

1. Ensure that the service is stopped before beginning:

[root@node1]# clusvcadm -d <service_name>

2. Remove any uncommented volume_list entries in /etc/lvm/lvm.conf on all cluster nodes (commenting them out is fine) and rebuild initramfs RAM Disk:

[root@node1]# vim /etc/lvm/lvm.conf
<comment or delete volume_list lines>
[root@node1]# grep volume_list /etc/lvm/lvm.conf | grep -v \#
<no output expected>
[root@node1]# dracut -H /boot/initramfs-$(uname -r).img $(uname -r)

[root@node2]# vim /etc/lvm/lvm.conf
<comment or delete volume_list lines>
[root@node2]# grep volume_list /etc/lvm/lvm.conf | grep -v \#
<no output expected>
[root@node2]# dracut -H /boot/initramfs-$(uname -r).img $(uname -r)

3. Ensure there are no tags remaining on the volume groups or logical volumes:

[root@node1]# vgs -a -o +tags
[root@node1]# lvs -a -o +tags

Follow the documentation for the process to enable HA-LVM CLVM variant: HA-LVM CLVM method.

Root Cause

There are currently 2 available variants of HA-LVM that can be configured: HA-LVM CLVM variant (preferred) and HA-LVM tagging variant
Red Hat recommend that HA-LVM CLVM-variant is used with LVM resources in Red Hat High Availability clusters.
- The CLVM-variant of HA-LVM is not appropriate in the following situations:
  - Stretch clusters
  - Customers who do not have Red Hat Enterprise Linux with Resilient Storage Add Ons (lvm2-cluster package is in resilient storage channels).
If you have previously set up tagging variant of HA-LVM, you may wish to switch to the CLVM-variant. This solution aims to help you do that.

Diagnostic Steps

This solution may be appropriate if you currently have HA-LVM tagging method configured on your cluster, and you want to switch to the HA-LVM CLVM method.
To check if you have HA-LVM tagging variant, you can check the following settings:
- Check if you have any LVM resources managed by your cluster? This is an indication that HA-LVM is configured, but not which variant:
```
# grep lvm /etc/cluster/cluster.conf
    <lvm lv_name="sanvol1" name="ha-lvm01" vg_name="sanvg1"/>
    <lvm lv_name="sanvol2" name="ha-lvm02" vg_name="sanvg2"/>
```
- Check if you have an uncommented volume_list entry in /etc/lvm/lvm.conf? If so, you're probably using HA-LVM tagging variant:
```
# grep volume_list /etc/lvm/lvm.conf | grep -v \#
volume_list = [ "rootvg", "@node1" ]
```
- Check the configured locking_type in /etc/lvm/lvm.conf. If locking_type= 1, you're probably using using HA-LVM tagging variant. If the type is 3, you're probably using CLVM variant:
```
# grep locking_type /etc/lvm/lvm.conf | grep -v \#
    locking_type = 1
```
- On the node that has your service activated, are there tags on your cluster-managed LVM volumes? The tags will be on the volume group if no lv_name is specified in /etc/cluster/cluster.conf, and on the logical volume if there is an lv_name specified in the resource definition. If there are tags on your logical volumes, it is very likely you are using HA-LVM tagging variant:
```
# vgs -a -o +tags
# lvs -a -o +tags
```

SBR

Clusterha

Product(s)

Red Hat Enterprise Linux

Components

lvm2

Tags

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