512 Implementing the IBM Storwize V5000
The volumes in this half of the consistency group are all operating in the secondary role
and can accept read I/O operations but not write I/O operations.
The consistency group does not contain any relationships.
10.2.3 Remote Copy planning
Before you use Remote Copy, you must plan for its usage.
General guidelines for Remote Copy
General guidelines for Remote Copy include the following considerations:
Partnerships between up to four IBM Storwize V5000 storage systems, IBM SAN Volume
Controller systems, IBM Storwize V7000, or IBM Storwize V3700 is allowed. The
partnership must be defined on any partnered IBM Storwize storage systems or IBM SAN
Volume Controller systems to make it fully functional.
The two volumes in a relationship must be the same size.
The Remote Copy relationship can be established on the volumes within one IBM
Storwize V5000 storage system or in different IBM Storwize V5000 storage systems.
When the two volumes are in the same cluster, they must be in the same I/O group.
You cannot use Remote Copy target volumes as Remote Copy source volumes. However,
a FlashCopy target volume can be used as Remote Copy source volume. Other
restrictions are outlined in Table 10-5 on page 514.
The Metro Mirror function supports copy operations between volumes that are separated
by distances up to 300 km.
One Remote Copy relationship can belong only to one consistency group.
All relationships in a consistency group must have matching primary and secondary
clusters, (master clusters and auxiliary clusters). All relationships in a consistency group
must also have the same copy direction and state.
Metro Mirror and Global Mirror relationships cannot belong to the same consistency
To manage multiple Remote Copy relationships as one entity, relationships can be made
part of a Remote Copy consistency group, which ensures data consistency across
multiple Remote Copy relationships and provides ease of management.
An IBM Storwize V5000 storage system implements flexible resynchronization support,
which enables it to resynchronize volume pairs that experienced write I/Os to both disks
and to resynchronize only those regions that are known to changed.
Global Mirror with Change Volumes should have Change Volumes that are defined for the
master and auxiliary volumes.