HP XP P9500 Storage - Manual (Page 134)

3. When Continuous Access Synchronous Z pair status is Duplex, create the Continuous Access
Journal Z pair on the primary system. The mirror ID must be set between 1 and 3.
Delta resync configuration
In a Continuous Access Journal Z delta resync configuration, you create a second Continuous
Access Journal Z pair in a 3DC multitarget. The pair is created using the Continuous Access
Synchronous Z secondary volume (R-VOL) and the Continuous Access Journal Z S-VOL, as illustrated
in the following. The delta resync operation requires less time to bring the S-VOL to a consistent
state after a failure occurs because only missing differential data needs to be copied. The delta
resync operation is performed when the primary site fails, as illustrated in the Delta Resync in a
Primary Site Disaster figure (below).
Figure 22 3DC multitarget with delta resync
Two operations are performed for the delta resync configuration:
•
Create the Continuous Access Journal Z delta resync pair
•
In a primary site disaster, perform the delta resync operation
The delta resync system is created after setting up the main Continuous Access Synchronous Z and
Continuous Access Journal Z pairs in the multitarget configuration.
•
Data is not copied at the time you set up the delta resync pair. The primary volume (P-VOL)
and S-VOL in this system contain data – from their respective Continuous Access Synchronous
Z and Continuous Access Journal Z systems.
•
If a failure on the primary site occurs, the Continuous Access Synchronous Z R-VOL is made
the primary production volume using the Business Continuity Manager commands . Differential
data stored in the journal volumes is used to synchronize the S-VOL, via the pairresync
operation.
Figure 23 Delta resync in a primary site disaster
134 Continuous Access Journal Z configurations with Continuous Access Synchronous Z