Restoring a pair of data volumes (pairresync), Restoring a pair, Restoring – HP XP Continuous Access Software User Manual
Page 192
The Pairsplit-r window shows the following:
•
S-VOL Write: Specify whether to permit hosts to write data to the secondary data volume. The
default is Disable (that is, do not permit).
◦
Disable: Hosts cannot write data to the secondary data volume while the pair is split.
◦
Enable: Hosts can write data to the secondary data volume while the pair is split. This
option is available only when the selected volume is a primary data volume.
•
Range: Specify the split range. The default is LU if two or more pairs in the same consistency
group are selected. The default is Group if not.
◦
LU: Only the specified pair is split.
If you select pairs with PAIR status or anything other than PAIR status in the same
consistency group, an unexpected suspension may occur during the pair operations
(Pairsplit-r, Pairsplit-S, and Pairresync) under heavy I/O load conditions. You can estimate
whether the I/O load is heavy or not from frequency of host I/Os. The suspend pair
operations should be performed under light I/O load conditions.
◦
Group: All pairs in the same consistency group(s) as the selected pairs are split.
Note: If the following two conditions are satisfied and you select Apply, a warning message
appears and processing cannot continue.
◦
The Preview list contains two or more pairs belonging to the same consistency group.
◦
The Range column show Group for at least one of the above pairs.
To continue processing, do one of the following:
◦
Ensure that the Range column shows LU for all pairs in the same consistency group.
◦
In the Preview list, select all but one pair in the same consistency group, right-click the
selected pairs, and then select Delete.
•
Suspend Mode: Specify how to deal with update data that has not been copied to the secondary
data volume. The default is Flush.
◦
Flush: When you split the pair, update data is copied to the secondary data volume.
When the secondary storage system receives a request for splitting a pair, all the journal
data (that is, update data) that the pair retains is written to the secondary data volume.
After that, the status of the pair changes from Suspending to PSUS if the pair does not
retain any journal data for a certain period of time.
◦
Purge: When you split the pair, the update data is not copied to the secondary data
volume. If you restore the pair later, the update data is copied to the secondary data
volume.
•
Set: Applies the settings to the Preview list in the Pair Operation window (
).
•
Cancel: Discards the settings and closes the window.
Restoring a Pair of Data Volumes (Pairresync)
Use the Pairresync window (
“Pairresync Window” (page 194)
) to restore a pair that has been split.
In addition, the window allows you to recover a mirror and start data copying of an XP Continuous
Access Journal pair in HOLD or HOLDING status in order to perform the delta resync operation.
If the primary or secondary storage system is powered off and its backup batteries are fully
discharged while pairs are suspended, the M-VOL/R-VOL bitmaps are not retained. In this unlikely
case, the primary/secondary storage system marks all cylinders/tracks of all suspended volumes
192 Performing XP Continuous Access Journal Pair Operations