Using Serviceguard Extension for RAC, 5th Edition, June 2007

Serviceguard Configuration for Oracle 9i RAC
Veritas Cluster Volume Manager (CVM) and Cluster File System (CFS)
Chapter 3138
Veritas Cluster Volume Manager (CVM) and
Cluster File System (CFS)
You may choose to configure cluster storage with the Veritas Cluster
Volume Manager (CVM) instead of the Volume Manager (VxVM). The
Base-VxVM provides some basic cluster features when Serviceguard is
installed, but there is no support for software mirroring, dynamic
multipathing (for active/active storage devices), or numerous other
features that require the additional licenses (on HP-UX releases that
support Veritas CFS and CVM; see “About Veritas CFS and CVM from
Symantec” on page 22).
VxVM supports up to 16 nodes, and CVM supports up to 8. CFS 5.0 also
supports up to 8 nodes; earlier versions of CFS support up to 4. The
VxVM Full Product and CVM are enhanced versions of the VxVM
volume manager specifically designed for cluster use. When installed
with the Veritas Volume Manager, the CVM add-on product provides
most of the enhanced VxVM features in a clustered environment. CVM is
truly cluster-aware, obtaining information about cluster membership
from Serviceguard directly.
Cluster information is provided via a special system multi-node package,
which runs on all nodes in the cluster. The cluster must be up and must
be running this package before you can configure VxVM disk groups for
use with CVM. Disk groups must be created from the CVM Master node.
The Veritas CVM package for version 3.5 is named VxVM-CVM-pkg; the
package for CVM version 4.1 and later is named SG-CFS-pkg. CVM
allows you to activate storage on one node at a time, or you can perform
write activation on one node and read activation on another node at the
same time (for example, allowing backups). CVM provides full mirroring
and dynamic multipathing (DMP) for clusters. CVM supports concurrent
storage read/write access between multiple nodes by applications which
can manage read/write access contention, such as Oracle Real
Application Cluster (RAC).