About delta resync – HP XP P9000 Command View Advanced Edition Software User Manual
Page 161
Copy type of the pair group to be connected by group addition
Copy type of
the original pair
group
Continuous Ac-
cess Journal
Continuous Access
Asynchronous
Continuous Ac-
cess Synchron-
ous
Snapshot
Business
Copy
Y
N
N
Y
Y
Continuous Ac-
cess Synchronous
N
N
N
Y
Y
Continuous Ac-
cess Asynchron-
ous
N
N
N
Y
Y
Continuous Ac-
cess Journal
Legend:
Y: This type of pair group can be connected.
N: This type of pair group cannot be connected.
Permitted topologies for cascade and multi-target configurations
The following restrictions apply when creating cascade or multi-target configurations or deleting copy
groups in cascade or multi-target configurations:
•
When creating a cascade configuration, it is necessary to first create a higher-level copy group.
Higher-level copy groups cannot be added to lower-level copy groups
•
When creating a cascade configuration, copy types and pair statuses of related copy groups must
be compatible
•
When deleting copy groups from a cascade configuration, you must first delete all lower-level
copy groups before deleting a higher-level copy group
•
The number of pairs that can be created varies depending on the storage system and copy type
About delta resync
In a 3DC multi-target configuration, there is one primary site and two secondary sites. Continuous
Access Synchronous and Continuous Access Journal are used to copy storage system volumes among
the three sites (called a data center). Continuous Access Journal provides the primary site and
Continuous Access Synchronous and Continuous Access Journal provide the secondary sites. Replication
Manager can be used to configure a Delta Resync pair using the two secondary sites. Delta Resync
pairs are stand-by pairs for providing additional redundancy in 3DC multi-target configurations.
Continuous Access Journal provides the delta resync operation as a way to recover from failures in
the primary site. If a failure occurs at the primary site in a 3DC multi-target configuration, the P9000
RAID Manager
horctakeover
command is used to reconfigure the Continuous Access Synchronous
secondary site as the primary site. If the delta re-synchronization function is used between the primary
and secondary sites, journal-copying of only the minimum data required is performed following a
failure, minimizing the recovery time.
Related topics
• Creating a 3DC multi-target configuration
• Limitations when performing 3DC configuration pair operations (mainframe systems)
User Guide
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