HP XP P9500 Storage - Manual (Page 136)

If any Continuous Access Journal Z pair in the journal group does not meet the above requirements,
an error occurs and delta resync operation will fail, even if the specified Continuous Access Journal
Z pair meets the requirements.
In the following cases, delta resync operation will not be performed because the necessary journal
data does not exist:
•
When, after creating the Continuous Access Journal Z pair, the primary data volume in the
Continuous Access Journal Z pair for delta resync operation is updated but Continuous Access
Journal Z primary data volumes (also used as Continuous Access Synchronous Z primary data
volumes) are not updated in the primary site.
•
When the volumes in the primary site are updated after splitting a Continuous Access
Synchronous Z pair.
•
When the secondary data volume is updated after splitting a Continuous Access Journal Z
pair.
•
When, after splitting a Continuous Access Journal Z pair and as a result of the update of the
primary data volume, the capacity of the journal data exceeds 70% of the journal volume in
the Continuous Access Synchronous Z secondary site.
•
When the primary data volume in the Continuous Access Journal Z pair for delta resync
operation is updated and then the capacity of the journal data exceeds 70% of the journal
volume in the primary site of a Continuous Access Journal Z pair for delta resync operation.
•
When, after creating the Continuous Access Journal Z pair for delta resync operation, no
volumes (including volumes after failover or failback) in the primary site are updated.
•
When a delta resync operation is performed while the Continuous Access Journal Z pair and
the Continuous Access Synchronous Z pair are in Duplex status, and within 5 minutes after a
volume in the primary site is updated after the Continuous Access Journal Z pair for delta
resync operation is created.
If the delta resync operation to support remote command devices is performed, you can execute
the delta resync operation from directly after the primary site is updated.
Consider the following when creating a Continuous Access Journal Z pair for delta resync
operation:
◦ When the Continuous Access Journal Z pair status changes to Hold after the delta resync
operation.
◦ When you create the Continuous Access Journal Z pair for delta resync operation when
recovering the primary site.
•
When the status of the Continuous Access Journal Z pair for delta resync operation becomes
Hlde, the journal data which is necessary for the delta resync operation might be discarded.
In that case, you cannot copy only differential data by performing the delta resync operation
even if the pair status is restored from Hlde to Hold. However, you can copy all the primary
volume data to the secondary volume.
To confirm whether it is possible to copy only differential data, execute the Business Continuity
Manager YKRESYNC DELTAJNL ERRCHK command.
By specifying an option, you can copy all the primary volume data to the secondary volume and
avoid the error when only a part of the differential data between primary and secondary data
volume is stored in the journal volume.
Procedure for creating a delta resync pair
To create a Continuous Access Journal Z pair for delta resync pair
1. Install and setup Continuous Access Synchronous Z and Continuous Access Journal Z on the
required storage systems.
136 Continuous Access Journal Z configurations with Continuous Access Synchronous Z