HP 3PAR Operating System Software - Manual (Page 271)

For additional information, see the following:
•
“Common Provisioning Groups” (page 108)
•
“Converting Standard Virtual Volumes” (page 106)
Snapshots in Synchronous Mode
In synchronous mode, remote copy creates snapshots only when:
•
An error occurs.
•
Disaster recovery is in process.
•
A volume group is manually stopped.
Use the createsv -rcopy command to create identical read-only snapshot volumes on both
the primary and secondary node.
The createsv command can also be used to create coordinated snapshots across a full remote-copy
group.
If group 1 contains vv.1, vv.2, ..., vv.n, the createsv command creates sv_vv.1_1,
sv_vv.2_1
, ..., vv.n_1. If, however, no pattern is included, then the is used as
a prefix, appended with a period (.).
Snapshots and Initial Synchronization Failure
If a failure occurs during the initial (full) synchronization of a virtual volume:
•
Remote copy does not create a snapshot of that volume.
•
After you recover the system and restart remote copy, remote copy performs another initial
(full) synchronization of the volume.
Snapshots and Resynchronization
During resynchronization:
•
The secondary volume state is syncing.
•
The secondary volume is not in a consistent state because updates are written by location
order rather than by time order.
•
When the resynchronization completes, remote copy deletes the snapshots on the primary
and the backup systems.
NOTE: For more information about deleted snapshots and space re-allocation, see “How CPGs
Allocate Space for Snapshots” (page 108) .
Snapshots and Resynchronization Failure in Synchronous Mode
If the primary system fails during a resynchronization, the secondary base volumes are left in an
inconsistent state, but the snapshots of the secondary volumes are left behind and not deleted.
After you recover the primary system, the next resynchronization brings the secondary volumes
back in synchronization with the primary volumes.
If the primary system fails during a resynchronization and you need to use the backup system to
access data, you must issue failover commands. For more information, see
“Recovering from
Disaster” (page 162) .
Snapshots in Synchronous Mode 271