Operating System Software Owner manual

For more information about snapshot creation, see “Remote Copy Snapshots” (page 203).
How Volume Groups Are Organized on the Remote Copy Pair
Primary volume groups store the virtual volumes to be copied. Under normal operating conditions:
• The data in the volumes in the primary volume groups is the most up-to-date.
• Primary volume groups reside on the primary system.
Secondary volume groups store the copied virtual volumes. Under normal operating conditions,
secondary volume groups reside on the backup system.
For more information on conditions that require you to temporarily switch the roles of the Remote
Copy volume groups, see “Recovering from Disaster” (page 102).
Natural Direction of Replication
The natural direction of Remote Copy replication is from the primary volume group to the secondary
volume group, which is from the primary to the backup system.
Linking Virtual Volumes in Volume Groups
As long as a secondary virtual volume is the same size as the primary volume, you can map any
primary virtual volume to any secondary volume in the secondary volume group.
Unidirectional Volume Groups
In unidirectional Remote Copy pairs, when you add virtual volumes to volume groups (using the
admitrcopyvv command), you map each virtual volume in the primary volume group on the
primary system to a virtual volume in the corresponding secondary volume group on the backup
system [Figure 34 (page 192)].
Figure 34 Mapping of Volumes between Unidirectional Primary and Backup Systems
Bidirectional Volume Groups
In bidirectional Remote Copy pairs, you can add primary volume groups to both the primary and
backup systems, and Remote Copy automatically creates secondary volume groups on the other
system in the Remote Copy pair.
In this configuration, each system provides backup for the primary volume groups on the other
system [Figure 35 (page 193)].
192 Volume Groups