Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

398 Administering cluster functionality
Cluster initialization and configuration
If you have RAID-5 volumes in a private disk group that you wish to make shareable, you
must first relayout the volumes as a supported volume type such as stripe-mirror or
mirror-stripe. Online relayout of shared volumes is supported provided that it does
not involve RAID-5 volumes.
If a shared disk group contains RAID-5 volumes, deport it and then reimport the disk
group as private on one of the cluster nodes. Reorganize the volumes into layouts that are
supported for shared disk groups, and then deport and reimport the disk group as shared.
Cluster initialization and configuration
Before any nodes can join a new cluster for the first time, you must supply certain
configuration information. The configuration information required by VxVM is as
follows:
■ cluster ID
■ node IDs
■ network addresses of nodes
■ port addresses
When a node joins the cluster, this information is automatically loaded into VxVM on that
node at node startup time.
Cluster startup effects node initialization, and brings up the various cluster components
including VxVM with cluster support, and the Serviceguard packages that control
applications, on the node.
For VxVM in a cluster environment, initialization consists of loading the cluster
configuration information and joining the nodes in the cluster. The first node to join
becomes the master node, and later nodes (slaves) join to the master. If two nodes join
simultaneously, VxVM chooses the master. Once the join for a given node is complete,
that node has access to the shared disk groups and volumes.
Cluster reconfiguration
Cluster reconfiguration occurs if a node leaves or joins a cluster. When the membership of
the cluster changes, the cluster monitor informs VxVM for it to take appropriate action.
During cluster reconfiguration, VxVM suspends I/O to shared disks. I/O resumes when
the reconfiguration completes. Applications may appear to freeze for a short time during
reconfiguration.
If other operations, such as VxVM operations or recoveries, are in progress, cluster
reconfiguration can be delayed until those operations have completed. Volume
reconfigurations (see “Volume reconfiguration” on page 401) do not take place at the
same time as cluster reconfigurations. Depending on the circumstances, an operation may