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Replicated Volume Group

A Replicated Volume Group (RVG) is a group of volumes within a given VxVM disk group configured for replication. An RVG is always a subset of a VxVM disk group. One or more related volumes in a disk group can be configured as an RVG. By related volumes, we mean a set of volumes to which application writes must be replicated in order on the Secondary.

In the case of a database, several processes perform writes to disks. Database processes write in a specific order. This order must be maintained at all times including when recovering from a disk failure. For example, the database posts any database change to the log before writing to the table space. To convey to VVR that these two volumes are related, these two volumes must be grouped.

All related volumes must be part of the same disk group. Unrelated volumes must not be grouped together in an RVG. Multiple RVGs can be configured inside one disk group, although this is not a recommended configuration.

Volumes that are associated with an RVG and contain application data are called data volumes. The data volumes in the RVG are under the control of an application, such as a Database Management System, that requires write-order fidelity among the writes to the volumes.

Write-ordering is strictly maintained within an RVG during replication to ensure that each remote volume is always consistent, both internally and with all other volumes of the group. Each RVG can have a maximum of 2048 data volumes. VVR replicates data from a Primary RVG, on the host where the application is running, to the Secondary RVG.

An RVG also contains the Storage Replicator Log (SRL) and Replication Link (RLINK), which are used internally by VVR. For more information, see Storage Replicator Log and Replication Link—RLINK.

  Note   A Primary RVG can have multiple Secondary RVGs. When this document refers to the Secondary host, it implicitly refers to all the Secondary RVGs.