Before you create a consistency group, consider its usage:
About this task
At which clusters is the underlying storage of the virtual volumes located? If volumes are at both clusters, set the storage-at-cluster property as
cluster-1,cluster-2.
What is the visibility of the virtual volumes to be added?
Some properties of virtual volumes and consistency groups limit which volumes can be added to a consistency group, or prevent a property of the consistency group from being modified.
For example, a consistency group’s
visibility property is set to
cluster-1. Virtual volumes local to cluster-1 are added. The
visibility property of the consistency group cannot be changed to either
cluster-2 or
cluster-1,cluster-2 since the volumes are not visible at cluster-2.
To create a consistency group and to configure those properties that should be set before virtual volumes are added, perform the following:
Steps
Use the
ls /clusters/*/consistency-groups/ command to display the names of all the consistency groups:
Use the
consistency-group create command to create a consistency group on a cluster. Specify a name for the new consistency group that did not appear in the output in the previous step.
Use the ls /clusters/cluster-id/consistency-groups/consistency-group/ command to display the new consistency group.
Setting the visibility property
By default, the consistency group’s
visibility property is set to the cluster where the consistency group was created. If a consistency group is created on cluster-2, it is initially visible only on cluster-2.
Visibility can be configured as follows:
cluster-1 - volumes local to cluster-1.
cluster-2 - volumes local to cluster-2.
cluster-1,cluster-2 - volumes that are distributed with legs at both clusters.
Use the
set command to configure the consistency group’s visibility property.
CAUTION:The CLI context of the consistency group appears only at the cluster where the consistency group has visibility. If visibility is set from cluster-1 to include only cluster-2, the CLI context for the consistency group disappears at cluster-1 and is visible only from cluster-2.
To set the consistency group’s visibility property to both clusters:
VPlexcli:/clusters/cluster-1/consistency-groups> set TestCG::visibility cluster-1,cluster-2
To set the consistency group’s visibility property to cluster-1:
VPlexcli:/clusters/cluster-1/consistency-groups> set TestCG::visibility cluster-1
To set the consistency group’s visibility property to cluster-2:
VPlexcli:/clusters/cluster-1/consistency-groups> set TestCG::visibility cluster-2
Setting the storage-at-clusters property
By default, the consistency group’s
storage-at-clusters property is set to empty.
The
storage-at-clusters field tells metro node at which cluster the physical storage that is associated with a consistency group is located. If
visibility is set to one cluster, then
storage-at-clusters must be the same as visibility. If
visibility is set to two clusters (1 and 2), then
storage-at-clusters can be one of:
cluster-1
cluster-2
cluster-1,cluster-2
A volume that does not have local storage at every cluster specified by the storage-at-clusters property of a consistency group, cannot be added to the consistency group.
Use the set command to configure the consistency group’s storage-at-clusters property
VPlexcli:/clusters/cluster-1/consistency-groups> set TestCG::storage-at-clusters cluster-1,cluster-2
Optionally, use one of the
consistency-group set-detach-rule commands to apply a detach rule.
For example, configure the detach-rule as
active-cluster-wins: