HP XP7 Storage - Manual (Page 128)

You create the delta resync configuration by adding a second Cnt Ac-J pair to the 3DC multi-target
configuration, using the Cnt Ac-S S-VOL and the Cnt Ac-J S-VOL, as illustrated in the following
figure. The delta resync operation is performed when the local site fails.
The following steps are used to set up and run the delta resync configuration:
1.
Create the Cnt Ac-J delta resync pair. See “Creating the delta resync pair” (page 128) .
2. Set up and map remote command devices and external ports in each site. With remote
command devices, sites automatically connect with each other. See
“Setting up remote
command devices” (page 129) .
3. Assign mirror IDs to remote command devices. See “Assigning mirrors to remote command
devices ” (page 130) .
4. In a recovery situation, run the delta resync operation. See “Performing the delta resync
operation” (page 132) .
Creating the delta resync pair
The delta resync system is created after setting up the main Cnt Ac-S and Cnt Ac-J pairs in the
multi-target configuration.
•
Data is not copied at the time you set up the delta resync pair. The P-VOL and S-VOL in this
system contain data from their respective Cnt Ac-S and Cnt Ac-J systems
•
If a failure on the local site occurs, the Cnt Ac-S S-VOL is made the primary production volume
using the the RAID Manager horctakeover command. Differential data stored in the journal
volumes is used to synchronize the S-VOL, via the pairresync operation.
Prerequisite information
•
A Cnt Ac-J delta resync pair can be created in a 3DC multi-target configuration only. To create
the multi-target configuration, see
“3DC multi-target configuration ” (page 126) .
•
A 3DC multi-target configuration with multiple primary and secondary systems cannot be used
for delta resync.
•
The Cnt Ac-S S-VOL is used as the delta resync P-VOL. It must be in PAIR status.
•
The Cnt Ac-J S-VOL is used as the delta resync S-VOL. It must be in PAIR status.
•
The mirror ID must be between 1 and 3; however, make sure it is not the same as the mirror
ID assigned to the Cnt Ac-J pair in the 3DC multi-target configuration.
•
The consistency group you use for the delta resync configuration cannot be used by another
Cnt Ac-J pair.
•
Follow volume combinations shown in “Volume types that can be shared with Continuous
Access Journal” (page 117) .
•
System option mode 506 must be ON for delta resync.
128 Configurations with Continuous Access Synchronous