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

or to abandon the transaction. Before the transaction can be committed, all of the
kernels ensure that no I/O is underway, and block any I/O issued by applications
until the reconfiguration is complete. The master node is responsible both for
initiating the reconfiguration, and for coordinating the commitment of the
transaction. The resulting configuration changes appear to occur simultaneously
on all nodes.
If a vxconfigd daemon on any node goes away during reconfiguration, all nodes
are notified and the operation fails. If any node leaves the cluster, the operation
fails unless the master has already committed it. If the master node leaves the
cluster, the new master node, which was previously a slave node, completes or
fails the operation depending on whether or not it received notification of
successful completion from the previous master node. This notification is
performed in such a way that if the new master does not receive it, neither does
any other slave.
If a node attempts to join a cluster while a volume reconfiguration is being
performed, the result of the reconfiguration depends on how far it has progressed.
If the kernel has not yet been invoked, the volume reconfiguration is suspended
until the node has joined the cluster. If the kernel has been invoked, the node
waits until the reconfiguration is complete before joining the cluster.
When an error occurs, such as when a check on a slave fails or a node leaves the
cluster, the error is returned to the utility and a message is sent to the console on
the master node to identify on which node the error occurred.
vxconfigd daemon
The VxVM configuration daemon, vxconfigd, maintains the configuration of
VxVM objects. It receives cluster-related instructions from the kernel. A separate
copy of vxconfigd runs on each node, and these copies communicate with each
other over a network. When invoked, a VxVM utility communicates with the
vxconfigd daemon running on the same node; it does not attempt to connect with
vxconfigd daemons on other nodes. During cluster startup, the kernel prompts
vxconfigd to begin cluster operation and indicates whether it is a master node
or a slave node.
When a node is initialized for cluster operation, the vxconfigd daemon is notified
that the node is about to join the cluster and is provided with the following
information from the cluster monitor configuration database:
■ cluster ID
■ node IDs
■ master node ID
Administering cluster functionality (CVM)
CVM initialization and configuration
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