HP XP P9500 Storage - Manual (Page 130)

B Continuous Access Journal Z configurations with
Continuous Access Synchronous Z
Continuous Access Journal Z and Continuous Access Synchronous Z can share the same data
volumes. Using Continuous Access Journal Z and Continuous Access Synchronous Z can extend
disaster recovery options to a third data center.
This appendix provides planning formation for sharing Continuous Access Journal Z volumes with
Continuous Access Synchronous Z. It describes four Continuous Access Journal Z/Continuous
Access Synchronous Z configurations.
In this appendix, P-VOL indicates the primary volume, and S-VOL indicates the secondary volume.
These terms are used for both Continuous Access Journal Z and Continuous Access Synchronous
Z.
Sharing volumes with Continuous Access Synchronous Z
Like Continuous Access Journal Z, a Continuous Access Synchronous Z pair maintains a copy of
the production volume in a second location. However, unlike Continuous Access Journal Z,
Continuous Access Synchronous Z’s secondary volume (R-VOL) is synchronous, and the remote
system is located within the same general region as the local site.
Creating a Continuous Access Journal Z backup and a Continuous Access Synchronous Z backup
insures that a copy in a third location is available in the event that the primary site, and possibly
one of the secondary sites, fail.
Continuous Access Journal Z and Continuous Access Synchronous Z can be used and configured
in a variety of ways. The following describes four principle configurations. These are covered in
detail in this appendix.
•
In a 3-Data Center Cascade configuration (3DC Cascade), three data centers are used — the
Continuous Access Synchronous Z production site, the Continuous Access Synchronous
Z/Continuous Access Journal Z intermediate site, and the distant Continuous Access Journal
Z remote site. The figure in the
“3 data center cascade configuration” (page 130) provides an
illustration. With this configuration, you can locate the Continuous Access Synchronous Z
synchronous site near the local site to lower I/O response time, while the Continuous Access
Journal Z backup provides a disaster recovery solution at a remote site.
•
In a 3 Data Center Multitarget configuration (3DC Multitarget), the production volume is shared
by the Continuous Access Synchronous Z and Continuous Access Journal Z. This volume is
the primary volume (P-VOL) for both at the local site. The targets of each system are located
at different remote sites. They provide the Continuous Access Synchronous Z solution and the
Continuous Access Journal Z asynchronous disaster recovery solution. The Continuous Access
Synchronous Z secondary site is at an intermediate location, the Continuous Access Journal
Z secondary site is at a distant location. This is illustrated in
“3 data center multitarget
configuration ” (page 132) .
•
Another use of the 3DC Multitarget is the Continuous Access Journal Z Delta Resync pair,
which provides a quick way to regain a long distance copy after disaster in the event that the
Continuous Access Synchronous Z/Continuous Access Journal Z M-VOL becomes unusable.
In this case, the host continues I/O operations at the intermediate Continuous Access
Synchronous Z R-VOL site. With a second Continuous Access Journal Z pair previously set up
between the Continuous Access Synchronous Z R-VOL and the Continuous Access Journal Z
S-VOL, only differential data needs to be copied to the Continuous Access Journal Z S-VOL.
Delta resync is illustrated in
“3 data center multitarget configuration ” (page 132) .
3 data center cascade configuration
As illustrated below, the Continuous Access Synchronous Z M-VOL is the primary production volume
in a 3DC cascade configuration. The Continuous Access Synchronous Z R-VOL is located at an
intermediate site that is near the primary site.
130 Continuous Access Journal Z configurations with Continuous Access Synchronous Z