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Replication in a shared disk group environment

VVR enables you to replicate data volumes in a shared disk group environment, for use with parallel applications that use Veritas Cluster Server (VCS) for high availability. You can replicate data volumes in a shared disk-group to a remote site, for disaster recovery or off-host processing.

A shared disk group is shared by all nodes in a cluster. A shared (or cluster-shareable) disk group is imported by all nodes in a cluster. Disks in a shared disk group must be physically accessible from all systems that join the cluster. VVR supports configurations in which both the Primary and Secondary disk group are shared, or either the Primary or the Secondary disk group is shared. If the Primary disk group is shared, the Secondary disk group need not be a shared disk group and vice versa.

When replicating data from a shared disk group to the remote site, VVR works with the cluster functionality of Veritas Volume Manager. The cluster functionality of VxVM requires that one node act as the master node; all other nodes in the cluster are slave nodes. See the Veritas Volume Manager Adminstrator's Guide for complete information on the cluster functionality (CVM) provided by VxVM.

VVR includes the VCS agents for VVR to provide support for VVR in a shared disk-group environment. For information about the agents, see the VCS Agents for VVR Configuration Guide. For information about VCS, see the Veritas Cluster Server documentation set.

  Note   Veritas Cluster Server is a separately licensed product. Veritas Cluster Server is not included with Veritas Volume Replicator. Veritas Cluster Volume Manager (cluster functionality) is included with Veritas Volume Manager, however you must have a separate license to use this feature. VVR also supports the cluster functionality of Veritas File System (VxFS), which is a separately licensed product.

The administrative model of the cluster functionality of VxVM requires you to run all commands on the master node. VVR adheres to the same model as CVM for most commands that change the configuration. However, some informational and administrative commands that are specific to VVR can be performed on any node in the cluster. These commands include vxrlink pause, vxrlink resume, vxrlink status, and vxrlink stats.

Note that the vxrlink status command and the vxrlink stats command display the same information on all the nodes in the cluster, whereas, the vxrvg stats command displays information pertaining to the node on which you run the command. The vxrvg stats command provides information about the reads and writes performed on the node on which you run it, therefore the information applies to that node only.