1.4. LVM Logical Volumes in a Red Hat High Availability Cluster
- High availability LVM volumes (HA-LVM) in an active/passive failover configurations in which only a single node of the cluster accesses the storage at any one time.
- LVM volumes that use the Clustered Logical Volume (CLVM) extensions in an active/active configurations in which more than one node of the cluster requires access to the storage at the same time. CLVM is part of the Resilient Storage Add-On.
1.4.1. Choosing CLVM or HA-LVM
- If multiple nodes of the cluster require simultaneous read/write access to LVM volumes in an active/active system, then you must use CLVMD. CLVMD provides a system for coordinating activation of and changes to LVM volumes across nodes of a cluster concurrently. CLVMD's clustered-locking service provides protection to LVM metadata as various nodes of the cluster interact with volumes and make changes to their layout.
- If the high availability cluster is configured to manage shared resources in an active/passive manner with only one single member needing access to a given LVM volume at a time, then you can use HA-LVM without the CLVMD clustered-locking service
1.4.2. Configuring LVM volumes in a cluster
- For a procedure for configuring an HA-LVM volume as part of a Pacemaker cluster, see An active/passive Apache HTTP Server in a Red Hat High Availability Cluster in High Availability Add-On Administration. Note that this procedure includes the following steps:
- Configuring an LVM logical volume
- Ensuring that only the cluster is capable of activating the volume group
- Configuring the LVM volume as a cluster resource