VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Administering Cluster Functionality
Cluster Initialization and Configuration
Chapter 10 349
Registration also sets up a callback mechanism for the cluster monitor to
notify the vxclustd daemon when cluster membership changes. After
initializing kernel cluster variables, the vxclustd daemon waits for a
callback from the cluster monitor. When the vxclustd daemon obtains
membership information from the cluster monitor, it validates the
membership change, and provides the new membership to the kernel.
The reconfiguration process continues within the kernel and the
vxconfigd daemon. This includes selection of a new master node if
necessary, initiation of communication between vxconfigd daemons on
the master and slave nodes, and a join protocol at the vxconfigd and
kernel levels that validates VxVM objects and distributes VxVM
configuration information across the cluster.
If reconfiguration completes successfully, the vxclustd daemon does not
take any further action; it waits for the next membership change from
the cluster monitor. If reconfiguration within the kernel or within the
vxconfigd daemon fails, the node must leave the cluster. The kernel
fails I/O in progress to shared disks, and stops access to shared disks and
the vxclustd daemon. The vxclustd daemon invokes the cluster
monitor command to halt the cluster on this node.
When a clean node shutdown is performed, vxclustd waits until kernel
cluster reconfiguration completes and then exits.
NOTE If MC/ServiceGuard is the cluster monitor, it expects the vxclustd
daemon registration to complete within a given timeout period. If
registration times out, MC/ServiceGuard aborts cluster initialization and
fails cluster startup.
Volume Reconfiguration
Volume reconfiguration is the process of creating, changing, and
removing VxVM objects such as disk groups, volumes and plexes. In a
cluster, all nodes cooperate to perform such operations. The vxconfigd
daemons (see “vxconfigd Daemon” on page 350) play an active role in
volume reconfiguration. For reconfiguration to succeed, a vxconfigd
daemon must be running on each of the nodes.
A volume reconfiguration transaction is initiated by running a VxVM
utility on the master node. The utility contacts the local vxconfigd
daemon on the master node, which validates the requested change. For