IBM Storwize V7000, Введение и руководство по внедрению

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Chapter 9. IBM Flex System V7000 Storage Node Copy Services
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Remote Copy relationships can only belong to one consistency group, but they do not have to
belong to a consistency group. Relationships that are not part of a consistency group are
called
stand-alone relationships
. A consistency group can contain zero or more relationships.
All relationships in a consistency group must have matching primary and secondary clusters,
which are sometimes referred to as
master
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 group.
A copy type is automatically assigned to a consistency group when the first relationship is
added to the consistency group. After the consistency group is assigned a copy type, only
relationships of that copy type can be added to the consistency group.
Remote Copy and consistency group states
Stand-alone Remote Copy relationships and consistency groups share a common
configuration and state model. All of the relationships in a non-empty consistency group have
the same state as the consistency group.
These states apply to both the relationships and the consistency groups, except for the Empty
state, which is only for consistency groups:
򐂰 InconsistentStopped:
The primary volumes are accessible for read and write I/O operations, but the secondary
volumes are not accessible for either one. A copy process must be started to make the
secondary volumes consistent.
򐂰 InconsistentCopying:
The primary volumes are accessible for read and write I/O operations, but the secondary
volumes are not accessible for either one. This state indicates that a copy process is
ongoing from the primary to the secondary volume.
򐂰
ConsistentStopped:
The secondary volumes contain a consistent image, but it might be out-of-date with
respect to the primary volumes. This state can occur when a relationship was in the
ConsistentSynchronized state and experiences an error that forces a freeze of the
consistency group or the Remote Copy relationship.
򐂰 ConsistentSynchronized:
The primary volumes are accessible for read and write I/O operations. The secondary
volumes are accessible for read-only I/O operations.
򐂰
Idling:
Both the primary volumes and the secondary volumes are operating in the primary role.
Consequently, the volumes are accessible for write I/O operations.
򐂰
IdlingDisconnected:
The volumes in this half of the consistency group are all operating in the primary role and
can accept read or write I/O operations.
򐂰 InconsistentDisconnected:
The volumes in this half of the consistency group are all operating in the secondary role
and cannot accept read or write I/O operations.
򐂰
ConsistentDisconnected:
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.
򐂰
Empty:
The consistency group does not contain any relationships.