HP XP P9500 Storage - Manual (Page 126)

A 3 Cnt Ac-J data-center configurations
With Continuous Access Journal, a volume at the primary site can be backed up to second and
third remote Cnt Ac-J sites in 3 data center (3DC) configurations.
This appendix provides planning and setup information for 3-Continuous Access Journal data
center configurations.
Overview
You can configure a Continuous Access Journal system using multiple P9500s in the following
configurations for disaster recovery:
•
3-data center cascade (3DC cascade). Data in the Cnt Ac-J P-VOL is paired with an S-VOL in
the Cnt Ac-J intermediate site; and then the intermediate site S-VOL is paired (becoming a
P-VOL) with an S-VOL in the Cnt Ac-J remote site. See the figure and information in
“3 Cnt
Ac-J DC cascade configuration” (page 126) .
•
3-data center multi-target configuration (3DC multi-target). Data in the Cnt Ac-J P-VOL is paired
with two S-VOLs—in two remote Cnt Ac-J locations. See the figure and information in
“3 Cnt
Ac-J DC multi-target configuration” (page 129)
•
An additional option for cascade and multi-target configurations is the delta resync, which
pairs the local P-VOL and one of the remote S-VOLs. The delta resync provides one more
option for maintaining a close copy of production data for use as a backup in the event of
failure at the other sites. The delta resync is slightly different for the cascading and mu lti-target
configurations. See the following sections for details.
•
3DC configurations can be set up using Continuous Access Synchronous and Cnt Ac-J also.
See
“Sharing volumes with Continuous Access Synchronous” (page 141) for information.
3 Cnt Ac-J DC cascade configuration
In a multi-target configuration, data is copied from the local site to two remote sites.In a cascading
configuration, data is copied from the primary (local) site to an intermediate site and then to a
remote site.
The intermediate site volume acts as:
•
The S-VOL for the local-intermediate pair
•
The P-VOL for with the intermediate-remote pair
In addition, you can create a delta resync pair from the local site to the remote site. Once created,
the delta resync pair remains split unless the S-VOL is needed for disaster recovery. Though the
pair is split, the S-VOL contains all but the latest production differential data. This is because the
volume is also the S-VOL for the pair from the intermediate site and so is updated regularly.
126 3 Cnt Ac-J data-center configurations