HP StorageWorks Application Recovery Manager Administrator's Guide (T4395-96004, February 2008)

Introduction
Concepts
Chapter 1 11
Backup with the XP VSS Hardware Provider
There are two configuration modes available for the backup with the XP
VSS hardware provider:
• VSS Compliant Mode
When the XP provider is in the VSS compliant mode, the source
volume (P-VOL) and its replica (S-VOL) are in simplex, unpaired
state after a backup. Therefore the number of replicas (S-VOLs per a
P-VOL) rotated is not limited. Restore from a backup in such a
configuration is possible only by switching of the disks.
• Resync Mode
When the XP provider is in the resync mode, the source volume
(P-VOL) and its replica (S-VOL) are in a suspended mirror
relationship after a backup. The maximum number of replicas
(S-VOLs per a P-VOL) rotated is three provided that MU range is 0-2
or 0, 1, 2. Restore from a backup in such a configuration is possible
only by re-synchronization of an S-VOL with its P-VOL.
Restore
Restore from ZDB-to-disk sessions is performed using instant recovery.
ZDB-to-disk session information is saved in the IDB, and the related
array-specific information required for instant recovery is saved in the
VSS database (VSSDB).
IMPORTANT During instant recovery, the whole replica is restored. This means not
only are the originally selected backup objects restored, but the complete
content of all the volume groups that contained them. After the instant
recovery, the content is returned to the states when the replica was
created.
Restore can be performed:
• Using Microsoft Virtual Disk Service (VDS)
With this method, a switch of a replica from the specified backup
session with the source volume is performed. Information about the
replica is deleted from the VSSDB, therefore, it is not possible to