HP StorageWorks XP Remote Web Console Software - Manual (Page 12)

Creation of an XP Snapshot Pair
An XP Snapshot pair uses a V-VOL as its S-VOL. Therefore, you need to create a V-VOL before
creating an XP Snapshot pair. In an XP Snapshot pair, up to 64 S-VOLs can be specified for a
P-VOL.
CAUTION: When you create an XP Snapshot pair, you decide which pool will be used by the
pair. If you create two or more XP Snapshot pairs that share the same P-VOL, you need to specify
the same pool for these pairs. For example, if you specify three S-VOLs for one P-VOL, you need
to specify the same pool for these three pairs.
When you delete an XP Snapshot pair, the status of the volumes becomes SMPL(PD). You cannot
create pairs by using SMPL(PD) volumes. If the volumes are in SMPL(PD) status, wait for a while
and issue the command to create pairs after the volume status changes to SMPL.
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.
Storing XP Snapshot Data
XP 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 a P-VOL.
To store snapshot data, you can use the RAID Manager command.
You can also store snapshot data for each consistency group by using RAID Manager. When you
store snapshot data by consistency group, data is copied as of the same point in time for all P-VOLs
in the group.
Figure 4 (page 13) shows an overview of storing snapshot data by a consistency
group.
12 About XP Snapshot Operations