HP StorageWorks Snapshot XP user guide (T1713-96023, October 2006)

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. IfSnapshotXPisnotusingthevolume,thevolumestatusisSMPL.IfSnapshotXPisusingthe

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 d ata, 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-VOLiswrittenbacktotheP-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 s

napshot data was stored by executing restoration.

To restor

e a Snapshot XP pair, use a RAID M anager 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 o perations 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 op erations 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

proces

sing caused by restore o perations when the array's load is heavy.

The Cop

y 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 a ccount support representative.

HP StorageWorks Snapshot XP user guide