HP 3PAR Operating System Software - Manual (Page 208)

Failure of All Links
When all links between storage systems in a Remote Copy pair fail, the two systems cannot
communicate. After failure of all links:
•
Both systems declare the other system to be down.
•
Both systems generate alerts regarding the other system’s failure.
The system handles complete link failure differently depending on whether the links are used for
synchronous or asynchronous periodic mode volume groups.
For more information about synchronous and asynchronous periodic volume groups, see “Volume
Group Modes” (page 194) .
Link Failure and Synchronous Volume Groups
For synchronous volume groups, when all links between a Remote Copy pair fail:
•
Remote Copy continues to allow writes to the primary volume group.
Therefore, applications that are writing data remain running even though the primary and
secondary volume groups go out of sync.
•
Remote Copy stops replication from the primary to the backup system.
•
Remote Copy creates snapshots of all primary virtual volumes that completed the initial
synchronization process.
•
While replication is stopped, Remote Copy does not create snapshots for secondary virtual
volumes.
•
The offset and length of the I/O fails to complete on the secondary virtual volumes because
the link failures were recorded in the nonvolatile memory.
The system records failed I/O replication separately because Remote Copy creates the
snapshots of the primary virtual volumes on the primary system after I/O is written to the
primary virtual volumes, but before Remote Copy can write the I/O to the secondary virtual
volumes.
Restarting Synchronous Volume Groups after Link Recovery
After you recover the links between the systems and Remote Copy marks the links as Up:
•
If the auto_recover policy is set, the volume groups automatically restart.
This policy only affects restarting after link failure. For more information, see “Automatically
Restarting Volume Groups” (page 89) .
•
If the no_auto_recover policy is set (the default), you must manually restart Remote Copy
on the systems in the Remote Copy pair.
To do so, issue the startrcopygroup command on the primary system. The
startrcopygroup
command synchronizes the systems:
◦ restarts replication for the volume groups
◦ reads the failed I/O from the primary virtual volumes and replicates it to the secondary
virtual volumes
◦ determines the difference between the base volume and the snapshot taken immediately
after replication stopped
◦ copies any new writes from the primary volume groups to the secondary volume groups
208 Error Handling