Support Policies for RHEL High Availability Clusters - LVM in a Cluster
Contents
Overview
Applicable Environments
- Red Hat Enterprise Linux (RHEL) with the High Availability Add-On
Useful References and Guides
Introduction
This guide offers Red Hat's policies around the usage of LVM within RHEL High Availability clusters. Users of RHEL High Availability clusters should adhere to these policies in order to be eligible for support from Red Hat with the appropriate product support subscriptions.
Policies
Cluster management of shared LVM: Clusters that share block storage devices and manage them with LVM must use one of the following methods for managing shared access to these devices in order to receive support from Red Hat:
- HA-LVM: Shared LVM volumes are activated by the cluster resource manager using an
LVM
orLVM-activate
resource (withpacemaker
) orlvm
resource (withrgmanager
). When usingLVM
resource and not managed byclvmd
orcontrold
resource, then/etc/lvm.conf
attribute should be set tolocking_type=1
. lvmlockd
in RHEL 8 Resilient Storage clusters with/etc/lvm.conf
attribute set tolocking_type=1
.clvmd
in RHEL 6 or 7 Resilient Storage clusters with/etc/lvm.conf
attribute set tolocking_type=3
.
Red Hat may be unable to provide support with cluster environments sharing LVM devices that do not use one of these facilities.
LVM RAID: Red Hat's support of shared LVM RAID volumes - volumes using any "raid
" segment type for mirroring - in a High Availability cluster is subject to the following conditions:
- RHEL 8 with the
LVM-activate
resource type: Supported by Red Hat - RHEL 7 with the
LVM
orLVM-activate
resource type: Supported by Red Hat withresource-agents-3.9.5-54.el7
or later, only when using tagging with avolume_list
. - RHEL 6 with
pacemaker
and theLVM
resource type: Supported by Red Hat withresource-agents-3.9.5-34.el6
or later, only when using tagging with avolume_list
. - RHEL 6 with
rgmanager
and thelvm
resource type: Supported by Red Hat withresource-agents-3.9.2-21.el6
or later, only when usingtagging
with avolume_list
. - Any RHEL release while using
lvmlockd
orclvmd
from Resilient Storage: Red Hat does not support usage of LVM RAID volumes with these clustered-LVM managers
LVM mirroring (non-RAID): Red Hat supports usage of clustered LVM mirrored volumes - those of the segment type mirror
- within RHEL High Availability clusters.
- RHEL 6: Supported with
clvmd
that managed the clustered logical volumes. - RHEL 7: Supported with
clvmd
via theclvm
resource-agent that managed the clustered logical volumes. - RHEL 8: The daemon
cmirrord
is deprecated and is incompatible with resource-agentlvmlockd
that is used to managed shared LVM volume groups on RHEL 8+. To usepvmove
on a shared volume group on RHEL 8 then see the following article: How topvmove
a volume that utilizeslvmlockd
shared activation on RHEL 8?
Use of cache
logical volumes in a cluster: Red Hat supports cache volumes in RHEL 8, in RHEL 7.1 or later and RHEL 6.7 or later.
Cache volumes can only be deployed in non-clustered volume groups - that is, VGs that are managed via an HA-LVM system through an LVM
or LVM-activate
resource (pacemaker
) or lvm
resource (rgmanager
). Cache volumes are not supported with lvmlockd
or clvmd
from the the Resilient Storage Add-On.
Cache volumes shared by a cluster must use writethrough
cache mode by way of allocation { cache_mode = "writethrough" }
in /etc/lvm/lvm.conf
.
lvm2-lvmetad
: With releases of lvm2
that provide support for lvm2-lvmetad
, clusters sharing access to LVM volumes must have lvm2-lvmetad
disabled in the configuration and as a service to prevent problems resulting from inconsistent metadata caching throughout the cluster.
- RHEL 8: The use of
lvm2-lvmetad
is deprecated and not supported and the attributeuse_lvmetad
no longer exists in/etc/lvm/lvm.conf
and the the systemd servicelvm2-lvmetad
no longer exists. - RHEL 6, 7:
lvm2-lvmetad
can be disabled in/etc/lvm/lvm.conf
in theglobal
section withuse_lvmetad=0
. -
RHEL 7:
lvm2-lvmetad
can be disabled and stopped at a service level usingsystemctl
:# systemctl disable lvm2-lvmetad # systemctl stop lvm2-lvmetad
-
RHEL 6:
lvm2-lvmetad
can be disabled at stopped at a service level usingchkconfig
andservice
:# chkconfig lvm2-lvmetad off # service lvm2-lvmetad stop
RHEL 6 ocf:heartbeat:LVM
resources with exclusive=true
and clvmd
: The ocf:heartbeat:LVM
resource type in RHEL 6 pacemaker
clusters must only be used with non-clustered volume groups if the resource must be exclusively-activated (using attribute exclusive=true
). Red Hat does not support the usage of LVM
resources with exclusive=true
managing a clustered volume group in RHEL 6. Exclusive volume groups must use the tagging method of HA-LVM management, which is achieved by ensuring the volume group does not have the clustered attribute enabled on it.
1 Comments
Is lvm2-lvmetad still availible in RHEL8? I wondered when reading the section about disabling it.