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Checking RPO — Monitoring P-VOL/S-VOL time difference
You can determine whether your desired RPO is being met by the TCE
system. Do this by monitoring the time difference between P-VOL data and
S-VOL data. See the section on synchronous waiting command
(pairsyncwait) in the Hitachi AMS Command Control Interface (CCI)
Reference Guide for details.
Routine maintenance
You may want to delete a volume pair, data pool, DMLU, or remote path.
The following sections provide prerequisites and procedures.
Deleting a volume pair
When a pair is deleted, the P-VOL and S-VOL change to Simplex status and
the pair is no longer displayed in the GUI Remote Replication pair list.
Please review the following before deleting a pair:
•
When a pair is deleted, the primary and secondary volumes return to
the Simplex state after the differential data accumulated in the local
array is updated to the S-VOL. Both are available for use in another
pair. Pair status is Paired:delete while differential data is transferred.
•
If failure occurs when the pair is Paired:delete, the data transfer is
terminated and the pair becomes Failure. While pair status changes to
Failure, it cannot be resynchronized.
•
Deleting a pair whose status is Synchronizing causes the status to
become Simplex immediately. In this case, data consistency is not
guaranteed.
•
A Delete Pair operation can result in the pair deleted in the local array
but not in the remote array. This can occur when there is a remote path
failure or the pair status on the remote array is Busy. In this instance,
wait for the pair status on the remote array to become Takeover, then
delete it.
•
Normally, a Delete Pair operation is performed on the local array where
the P-VOL resides. However, it is possible to perform the operation from
the remote array, though with the following results:
-
Only the S-VOL becomes Simplex.
-
Data consistency in the S-VOL is not guaranteed.
-
The P-VOL does not recognize that the S-VOL is in Simplex status.
Therefore, when the P-VOL tries to send differerential data to the
S-VOL, it sees that the S-VOL is absent, and P-VOL pair status
changes to Failure.
-
When a pair's status changes to Failure, the status of the other
pairs in the group also becomes Failure.
•
After an SVOL_Takeover command is issued, the pair cannot be deleted
until S-VOL data is restored from the remote data pool.
Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide
Monitoring and maintenance
9–9
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Troubleshooting
