HP XP P9500 Storage - Manual (Page 134)

Delta resync configuration
In a Continuous Access Journal delta resync configuration, you create a second Continuous Access
Journal pair in a 3DC multitarget. The pair is created using the Continuous Access Synchronous
secondary volume (S-VOL) and the Continuous Access Journal 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 21 3DC multitarget with delta resync
Two operations are performed for the delta resync configuration:
•
Create the Continuous Access Journal 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 and
Continuous Access Journal 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
and Continuous Access Journal systems
•
If a failure on the primary site occurs, the Continuous Access Synchronous S-VOL is made the
primary production volume using the RAID Manager horctakeover command. Differential
data stored in the journal volumes is used to synchronize the S-VOL, via the pairresync
operation.
Figure 22 Delta resync in a primary site disaster
134 Continuous Access Journal configurations with Continuous Access Synchronous