HP XP P9500 Storage - Manual (Page 140)

Figure 58 Snapshot and volume mapping
Snapshot volumes
The specifications for Snapshot volumes are:
•
Allowable type of paired volume: The supported volume type is OPEN-V only for P VOL, and
OPEN-0V for S VOL.
•
Number of volumes (Snapshot) can be paired: This depends on P VOL capacity, Snapshot
pool capacity, and shared memory capacity on the RAID storage system.
•
Duplicated writing mode: Copying on write.
•
Number of mirror volumes: Up to 64 secondary volumes can be defined for each P VOL.
For details on Snapshot specifications such as maximum number of mirrored volumes, volumes
and operations, please see the HP P9000 Snapshot User Guide for your storage system.
Creating a Snapshot pair
The RAID Manager command for creating a Snapshot pair is the same as for Business Copy. The
RAID storage system detects whether the pair is a Business Copy or Snapshot pair by the LDEV
attribute of the S-VOL. A Snapshot pair is generated in the following two cases.
•
When a V-VOL unmapped to the S-VOL of a Snapshot called OPEN-0V is specified as an
S-VOL.
•
When an S-VOL is not specified.
A V-VOL has the following characteristics:
•
It appears as “OPEN-0V” to identify a V-VOL easily via the SCSI Inquiry or RAID Manager.
•
A V-VOL unmapped to the S-VOL of a Snapshot will reply to a SCSI Inquiry, but Reading
and/or Writing is not allowed. LDEV will reply the capacity setting as an LU to SCSI Read
Capacity.
•
A V-VOL that has become the S-VOL of a Snapshot will reply to a SCSI Inquiry, and Reading
and/or Writing is allowed.
Snapshot pair status
Each paired volume consists of a primary volume (P-VOL) and a secondary volume (S-VOL). Each
volume has the status for controlling the pair state.
The P-VOL controls the pair state that is reflected on the status of the S-VOL. The major pair statuses
are “SMPL”, “PAIR”, “PSUS”, “COPY”, and “RCPY”. The status is changed when the RAID Manager
140 Data replication operations with RAID Manager