Administrator Guide

Table 11. Consistency group field descriptions (continued)
Property Description
operational status
Current status for this consistency group with respect to each cluster on which it
is visible.
● ok - I/O can be serviced on the volumes in the consistency group.
● suspended - I/O is suspended for the volumes in the consistency group.
The reasons are described in operational status: details.
● degraded - I/O is continuing, but there are other problems as described in
operational status: details.
● unknown - The status is unknown, mostly because of lost management
connectivity.
operational status: details
If operational status is ok, this field is empty: [ ]. Otherwise, it displays
additional information, which may be any of the following:
● cluster-departure - Not all the visible clusters are in communication.
● data-safe-failure - A single director has failed. The volumes are still
crash-consistent, and remain in this state, unless a second failure occurs
before the first is recovered.
● rebuilding-across-clusters - One or more distributed member
volumes is being rebuilt. At least one volume in the group is out of date at
that cluster and is re-syncing. If the link goes out at this time, the entire
consistency group is suspended. Use the rebuild status command to
display which volume is out of date at which cluster.
● rebuilding-within-cluster - One or more local rebuilds is in progress at this
cluster.
● requires-resolve-conflicting-detach - After the inter-cluster link
is restored, two clusters have discovered that they have detached from
one another and resumed I/O independently. The clusters are continuing to
service I/O on their independent versions of the data. The consistency-
group resolve-conflicting-detach command must be used to make
the view of data consistent again at the clusters.
● requires-resume-after-rollback - A cluster has detached its peer
cluster and rolled back the view of data, but is awaiting the consistency-
group resume-after-rollback command before resuming I/O.
Displayed:
○ There is no detach-rule
○ If the detach-rule is no-automatic-winner, or
○ If the detach-rule cannot fire because its conditions are not met.
￭ unhealthy-devices - I/O has stopped in this consistency group
because one or more volumes are unhealthy and cannot perform I/O.
￭ will-rollback-on-link-down - If there were a link-down now,
the winning cluster would have to roll back the view of data in order to
resume I/O.
virtual-volumes
List of virtual volumes that are members of the consistency group.
Operating a consistency group
Best practice is to allow I/O to continue at only one cluster. Allowing I/O to continue at both clusters will result in the complete
resync of one cluster from the other. All writes at the loser cluster are lost.
About this task
When I/O continues at both clusters:
● The data images at the clusters diverge.
● Legs of distributed volumes are logically separate.
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Consistency Groups