Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

then join it back into the cluster. This operation is repeated for each node in the
cluster.
Each Veritas Volume Manager release starting with Release 3.1 has a cluster
protocol version number associated with it. The cluster protocol version is not
the same as the release number or the disk group version number. The cluster
protocol version is stored in the /etc/vx/volboot file. During a new installation
of VxVM, the vxdctl init command creates the volboot file and sets the cluster
protocol version to the highest supported version.
Each new Veritas Volume Manager release supports a minimum and maximum
cluster protocol version. Each protocol version supports a fixed set of features
and communication protocols. When a new release of VxVM adds new features
or communication protocols, a new version number is assigned. If the new release
of VxVM does not include new features or communication protocols, but only
includes bug fixes or minor changes, the cluster protocol version remains
unchanged. The maximum version number corresponds to the latest release of
VxVM. The cluster protocol version generally does not need to be upgraded
manually.
This version of Veritas Volume Manager (VxVM) does not support the rolling
upgrade feature.
Dirty region logging 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 how DRL
behaves in a cluster environment.
In a cluster environment, the VxVM implementation of DRL differs slightly from
the normal implementation.
A dirty region log on a system without cluster support has a recovery map and a
single active map. A dirty region log in a cluster, however, has one recovery map
and one active map for each node in the cluster.
The dirty region log size in clusters is typically larger than in non-clustered
systems, as it must accommodate a recovery map plus active maps for each node
in the cluster. The size of each map within the dirty region log is one or more
whole blocks. The vxassist command automatically allocates a sufficiently large
dirty region log for the size of the volume and the number of nodes.
It is possible to reimport a non-shared disk group (and its volumes) as a shared
disk group in a cluster environment. However, the dirty region logs of the imported
disk group may be considered invalid and a full recovery may result.
Administering cluster functionality
Dirty region logging in cluster environments
472