Dell EMC Metro node 7.0.1 Administrator Guide

Creating a consistency group

Before you create a consistency group, consider its usage:

1. Use the ls /clusters/*/consistency-groups/ command to display the names of all the consistency groups:

   VPlexcli:/> ls /clusters/*/consistency-groups/
   /clusters/cluster-1/consistency-groups:
   TestCG         local_test     test10      test11     test12  test13  test14
   test15         test16         test5       test6      test7   test8   test9
   vs_RAM_c1wins  vs_RAM_c2wins  vs_oban005  vs_sun190
   /clusters/cluster-2/consistency-groups:
   TestCG         local_test     test10      test11     test12  test13  test14
   test15         test16         test5       test6      test7   test8   test9
   vs_RAM_c1wins  vs_RAM_c2wins  vs_oban005  vs_sun190

2. 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.

   VPlexcli:/> consistency-group create --name TestCG --cluster cluster-1

3. 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.
4. 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.

5. 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

6. 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:

   VPlexcli:/clusters/cluster-1/consistency-groups/TestCG> set-detach-rule active-cluster-wins

7. Use the ll command to display the new consistency group.

   See Table 16 Consistency group field descriptions for descriptions of the fields in the display.