VERITAS Volume Manager 4.1 Administrator's Guide

Administering Cluster Functionality
Dirty Region Logging (DRL) in Cluster Environments
Chapter 10368
Each new Volume Manager release supports two cluster protocol
versions. The lower version number corresponds to a previous Volume
Manager release. This has a fixed set of features and communication
protocols. The higher version number corresponds to the new release of
VxVM which has a new set of these features. If the new release of VxVM
does not have any functional or protocol changes, but only bug fixes or
minor changes, the cluster protocol version remains unchanged. In this
case, the cluster protocol version does not need to be upgraded.
During a rolling upgrade, each node must be shut down and the Volume
Manager release with the latest cluster protocol version must be
installed. All nodes that have the new release of VxVM continue to use
the lower level version. A slave node that has the new cluster protocol
version installed tries to join the cluster. If the new cluster protocol
version is not in use on the master node, it rejects the join and provides
the current cluster protocol version to the slave node. The slave retries
the join with the cluster protocol version provided by the master node. If
the join fails at this point, the cluster protocol version on the master node
is out of range of the protocol versions supported by the joining slave. In
such a situation, you must upgrade the remainder of the cluster through
each intermediate release of VxVM to reach the latest supported cluster
protocol version.
Once you have installed the new release on all nodes, run the vxdctl
upgrade command on the master node to switch the cluster to the higher
cluster protocol version. See “Upgrading the Cluster Protocol Version” on
page 380 for more information.
Dirty Region Logging (DRL) in Cluster
Environments
Dirty region logging (DRL) is an optional property of a volume that
provides speedy recovery of mirrored volumes after a system failure.
DRL is supported in cluster-shareable disk groups. This section provides
a brief overview of DRL and describes how DRL behaves in a cluster
environment. For more information on DRL, see “Dirty Region Logging
(DRL)” on page 46.