HP StorageWorks XP Remote Web Console Software - Manual (Page 19)

NOTE:
When deleting a Snapshot XP pair, the volumes' status becomes SMPL(PD). You cannot create pairs
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 volumes' status changes to SMPL.
Use the Business Copy XP main pane to see the volume's status. Using RAID Manager XP, you can
check the volume status with the pairdisplay command, but you cannot distinguish between SMPL and
SMPL(PD) volumes. To distinguish between SMPL and SMPL(PD) volumes using RAID Manager XP,
issue the inqraid command as well. The inqraid command shows whether Snapshot XP is using the
volume. If Snapshot XP is not using the volume, the volume status is SMPL. If Snapshot XP is using the
volume, the volume status is SMPL(PD).
Storing snapshot data
Snapshot data is a replica of data in a Snapshot XP pair's P-VOL, and is stored in a pool. When the
P-VOL is updated, updated 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 a Snapshot XP pair to store snapshot data, the snapshot data is stored in the
pool when a host issues a write request to the Snapshot XP pair's P-VOL.
To store snapshot data in a pool, use a RAID Manager XP command. For more information, see
Storing snapshot data .
Restoring Snapshot XP pairs
Snapshot XP can restore a P-VOL's contents 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 a Snapshot XP pair.
NOTE:
If you restore the pair when data is written in the S-VOL instead of the snapshot data, data in the
S-VOL is written back to the P-VOL.
If there are problems with the P-VOL data during a failure, you can restore the P-VOL to the normal state
when the snapshot data was stored by executing restoration.
To restore a Snapshot XP pair, use a RAID Manager command. For more information, see
Restoring
Snapshot XP pairs .
Copy Threshold option: If the array's load increases, host server I/O performance (response) might be
degraded. If Snapshot XP performs restore operations when the array's load is heavy, it is more likely
that host server I/O performance (response) might be degraded. The Copy Threshold option temporarily
stops copy processing caused by restore operations when the array's load is heavy. If you enable
this option, you can minimize the degradation of host I/O performance by temporarily stopping copy
processing caused by restore operations when the array's load is heavy.
The Copy Threshold option is effective only when the array's load is heavy. When the Copy Threshold
option is enabled, all copy processing by restore operations stops. For more information about setting the
Copy Threshold option, contact your HP account support representative.
HP StorageWorks Snapshot XP user guide 19