Installation guide

The Cluster Logical Volume Manager (CLVM) provides a cluster-wide version of LVM2. CLVM

provides the same capabilities as LVM2 on a single node, but makes the volumes available to all

nodes in a Red Hat cluster. The logical volumes created with CLVM make logical volumes available

to all nodes in a cluster.

The key component in CLVM is clvmd. clvmd is a daemon that provides clustering extensions to the

standard LVM2 tool set and allows LVM2 commands to manage shared storage. clvmd runs in each

cluster node and distributes LVM metadata updates in a cluster, thereby presenting each cluster

node with the same view of the logical volumes (refer to Figure 1.11, “CLVM Overview” ). Logical

volumes created with CLVM on shared storage are visible to all nodes that have access to the shared

storage. CLVM allows a user to configure logical volumes on shared storage by locking access to

physical storage while a logical volume is being configured. CLVM uses the lock-management

service provided by the cluster infrastructure (refer to Section 1.3, “ Cluster Infrastructure” ).

Note

Shared storage for use in Red Hat Cluster Suite requires that you be running the cluster

logical volume manager daemon (clvmd) or the High Availability Logical Volume Management

agents (HA-LVM). If you are not able to use either the clvmd daemon or HA-LVM for

operational reasons or because you do not have the correct entitlements, you must not use

single-instance LVM on the shared disk as this may result in data corruption. If you have any

concerns please contact your Red Hat service representative.

Note

Using CLVM requires minor changes to /etc/lvm/lvm.conf for cluster-wide locking.

⁠Chapt er 1 . Red Hat Clust er Suit e Overview