Managing Serviceguard Eighteenth Edition, September 2010

• need to use software RAID mirroring or striped mirroring.
• have multiple heartbeat subnets configured.
Propagation of Disk Groups in VxVM
A VxVM disk group can be created on any node, whether the cluster is up or not. You
must validate the disk group by trying to import it on each node.
Package Startup Time with VxVM
With VxVM, each disk group is imported by the package control script that uses the
disk group. This means that cluster startup time is not affected, but individual package
startup time might be increased because VxVM imports the disk group at the time the
package starts up.
Veritas Cluster Volume Manager (CVM)
NOTE: Check the Serviceguard/SGeRAC/SMS/Serviceguard Manager Plug-in Compatibility
and Feature Matrix and the latest Release Notes for your version of Serviceguard for
up-to-date information on CVM support: www.hp.com/go/
hpux-serviceguard-docs.
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.
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 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).
Volume Managers for Data Storage 113