Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

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. After a given node joins,
that node has access to the shared disk groups and volumes.
Cluster reconfiguration
Cluster reconfiguration occurs if a node leaves or joins a cluster. Each node’s
cluster monitor continuously watches the other cluster nodes. 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 complete. Volume
reconfigurations do not take place at the same time as cluster reconfigurations.
Depending on the circumstances, an operation may be held up and restarted later.
In most cases, cluster reconfiguration takes precedence. However, if the volume
reconfiguration is in the commit stage, it completes first.
See “Volume reconfiguration” on page 443.
See “vxclustadm utility” on page 441.
vxclustadm utility
The vxclustadm command provides an interface to the CVM functionality of VxVM
when HP Serviceguard is used as the cluster monitor. It is also called during cluster
startup and shutdown. In the absence of a cluster monitor, vxclustadm can also
be used to activate or deactivate the CVM functionality of VxVM on any node in
a cluster.
The startnode keyword to vxclustadm starts CVM functionality on a cluster node
by passing cluster configuration information to the VxVM kernel. In response to
this command, the kernel and the VxVM configuration daemon, vxconfigd,
perform initialization.
The stopnode keyword stops CVM functionality on a node. It waits for all
outstanding I/O to complete and for all applications to close shared volumes.
The setmaster keyword migrates the CVM master to the specified node. The
migration is an online operation. Symantec recommends that you switch the
441Administering cluster functionality (CVM)
CVM initialization and configuration