HP StorageWorks XP Remote Web Console Software - Manual (Page 13)

consistency group (3 in Figure 4 (page 12) ), snapshot data of corresponding volume is stored (4
in Figure 4 (page 12) ).
You can also use the RAID Manager commands to store snapshot data by a consistency group.
From XP Remote Web Console, you can only view the consistency groups.
XP Snapshot does not support Quick Split mode. Therefore, even if you specify Quick Split mode,
Quick Split mode does not take effect.
Restoration of an XP Snapshot Pair
XP Snapshot can restore the contents of the P-VOL to the state when the snapshot data was stored
in the pool by writing the snapshot data back to the P-VOL. Writing the snapshot data to the P-VOL
is called restoration of the XP Snapshot pair.
If you restore the pair when the data is written in the S-VOL, instead of the snapshot data, the data
in the S-VOL will be written back to the P-VOL.
If there are problems with the data of a P-VOL during a failure, you can restore the P-VOL to the
normal state when the snapshot data was stored by executing restoration.
Deletion of XP Snapshot Data or an XP Snapshot Pair
The status of the XP Snapshot pair will be PSUE (status when the failure occurred) when, as a result
of writing data in the volume of that pair, the capacity of snapshot data exceeds the capacity of
the pool specified when the pool was defined. An XP Snapshot pair cannot be created and snapshot
data cannot be stored in the pool. Therefore, unnecessary snapshot data needs to be deleted.
There are two ways to delete snapshot data:
•
Delete the XP Snapshot pair itself.
•
Delete only the snapshot data.
When an XP Snapshot pair is deleted, not only is the snapshot data stored in the pool deleted,
but also the relationship between the P-VOL and the S-VOL will be released. If only the snapshot
data is deleted, the relationship between the P-VOL and the S-VOL is maintained. When only the
snapshot data is deleted, the snapshot ID of the deleted snapshot data can be assigned to the
newly stored snapshot data of the XP Snapshot pair.
After the command is issued to delete snapshot data, no more snapshot data of that XP Snapshot
pair will be stored in the pool, even if the host tries to write data in the P-VOL. To store snapshot
data for that XP Snapshot pair again, you need to issue the command for storing snapshot data.
The required time for deleting snapshot data or XP Snapshot pairs is several seconds, and sometimes
more than ten minutes. The time will increase if the deleted pair uses a large amount of the pool,
or if multiple pairs are deleted at one time.
When you delete an XP Snapshot pair, the status of the volumes becomes SMPL(PD). Use the XP
Business Copy's Pair Operation window to see the status of the volume.
Using RAID Manager, you can check the volume status by the pairdisplay command, but you
cannot distinguish between an SMPL volume and an SMPL(PD) volume. To distinguish between an
SMPL volume and an SMPL(PD) volume by using RAID Manager, you need to issue the inqraid
command as well. The inqraid command will show you whether or not the volume is being used
by XP Snapshot. As a result of the inqraid command, if the volume is not used by XP Snapshot,
the volume status is SMPL. If the volume is used by XP Snapshot, the status of the volume is SMPL(PD).
NOTE: When using the inqraid command, specify the -fw option of the XP Snapshot pair IDs
from 3 to 63.
Status of the XP Snapshot Pairs
When you create or split an XP Snapshot pair, the status of the pair changes. Page 14 shows the
transition of the status of an XP Snapshot pair.
Status of the XP Snapshot Pairs 13