IBM Storwize V5010 Manual page 584

Figure 10-79 shows the concept of Metro Mirror Consistency Groups. The same applies to
Global Mirror Consistency Groups.
Figure 10-79 Metro Mirror Consistency Group
Because the MM_Relationship 1 and 2 are part of the Consistency Group, they can be
handled as one entity. The stand-alone MM_Relationship 3 is handled separately.
Certain uses of MM/GM require the manipulation of more than one relationship. Remote
Copy Consistency Groups can group relationships so that they are manipulated in unison.
Consider the following points:
MM/GM relationships can be part of a Consistency Group, or they can be stand-alone
and, therefore, are handled as single instances.
A Consistency Group can contain zero or more relationships. An empty Consistency
Group with zero relationships in it has little purpose until it is assigned its first relationship,
except that it has a name.
All relationships in a Consistency Group must have corresponding master and auxiliary
volumes.
All relationships in one Consistency Group must be the same type, for example only Metro
Mirror or only Global Mirror.
Although Consistency Groups can be used to manipulate sets of relationships that do not
need to satisfy these strict rules, this manipulation can lead to undesired side effects. The
rules behind a Consistency Group mean that certain configuration commands are prohibited.
These configuration commands are not prohibited if the relationship is not part of a
Consistency Group.
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Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.1