HP 3PAR Operating System Software - Manual (Page 112)

Rules for Forming Volume Groups
The group of virtual volumes in a remote-copy volume group:
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Must be located on the same storage system.
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Can be logically related.
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Can be volumes for which there is a cross-volume ordering of writes.
•
Must not exceed the maximum (300).
•
Must be one of these types:
TPVVs with snapshot space ◦
◦ FPVVs
◦ RW snapshots (see “Rules for Adding Snapshots to Volume Groups” (page 112) )
For additional information, see “Limits on Volumes that Concurrently Synchronize” (page 123)
How Volume Groups Are Named
When you create and name a volume group on the primary system (using the creatercopygroup
command), HP 3PAR Remote Copy automatically creates and names the associated secondary
volume group on the backup system. The secondary volume group is named:
<primary_group_name>.r<primary_system_system_ID>
For example, if the primary volume group is Group1 and the primary system ID is 96, HP 3PAR
Remote Copy names the secondary volume group Group1.r96.
For additional information, see the following:
•
“Creating Volume Groups for Unidirectional Remote Copy” (page 82)
•
“About the Remote-Copy Commands” (page 261)
Rules for Adding Snapshots to Volume Groups
You can add RW snapshots to a volume group:
•
You can add one RW snapshot per virtual volume to a volume group.
•
You cannot add both a snapshot and the base volume for that snapshot to the same volume
group.
•
You cannot add a snapshot to more than one volume group.
NOTE: In HP 3PAR OS 2.3.1, RW snapshots cannot be added to remote-copy volume groups.
For more information, see “Rules for Forming Volume Groups” (page 112) .
For more information about snapshot creation, see “Remote-Copy Snapshots” (page 270) .
How Volume Groups Are Organized on the Remote-Copy Pair
Primary volume groups contain the virtual volumes to be replicated. Under normal operating
conditions:
•
The data in the volumes in the primary volume groups is the most up-to-date.
•
Primary volume groups are kept on the primary system.
Secondary volume groups contain the replicated virtual volumes. Under normal operating conditions,
secondary volume groups are kept on the backup system.
For more information about conditions that require you to temporarily switch the roles of the
remote-copy volume groups, see
“Recovering from Disaster” (page 162) .
112 Working with Volume Groups