HP StorageWorks XP Remote Web Console Software - Manual (Page 14)

Use 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).
Storing of Snapshot Data
Snapshot data is a replica of data in the P-VOL of an XP Snapshot pair, and is stored in a pool. When
the P-VOL is updated, the updated part of the data is copied to the pool as snapshot data before the
P-VOL is updated. This process is called storing snapshot data.
If you issue a command to an XP Snapshot pair to store snapshot data, the snapshot data will be stored
in the pool later, at the time a host makes a write request to the P-VOL of an XP Snapshot pair. An XP
Snapshot pair can store up to 64 snapshot data per P-VOL.
To store snapshot data in a pool, use a command of RAID Manager. For details about the operation
to store snapshot data, see “ Storing Snapshot Data ” on page 64.
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.
Note: 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.
To restore an XP Snapshot pair, use a command of RAID Manager. For details about the operation of
restoration, see “ Restoring XP Snapshot Pairs ” on page 65.
Deletion of Snapshot Data or an XP Snapshot Pair
The status of the XP Snapshot pair will be PSUE (status when 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. One way is to delete the XP Snapshot pair itself, and the other way is to
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. On the other hand, 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.
To delete an XP Snapshot pair or snapshot data, use a command of RAID Manager. However, when
deleting an XP Snapshot pair, you can also use the Pairsplit -S dialog box of Remote Web Console. For
details about deleting snapshot data, see “ Deleting Snapshot Data ” on page 65. For details about
deleting an XP Snapshot pair, see “ Deleting XP Snapshot Pairs ” on page 65.
Notes:
• 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.
14 About XP Snapshot Operations