Consistency and snapshot groups

Consistency groups and snapshot groups are groups of pairs for which you can simultaneously perform pair tasks on all pairs within the group.

A consistency group can include Thin Image (HTI), ShadowImage (SI), and ShadowImage for Mainframe (SIz) pairs. Use consistency groups to split the Thin Image pairs that are defined in the group. Splitting the pairs using the group assures data consistency at the time the VSP family storage system receives the request.

A snapshot group is a group of only Thin Image pairs. Use consistency or snapshot groups to perform Thin Image tasks on all of the pairs within the group. You define Thin Image pairs to a snapshot group when you create the pairs.

The following table shows the differences between consistency groups and snapshot groups.

For more information about defining TC pairs in consistency groups, see the TrueCopy User Guide.

For more information about defining UR pairs in consistency groups, see the Universal Replicator User Guide.

For more information about defining SI pairs in consistency groups, see the ShadowImage User Guide.

Related Concepts

• Workflow for creating groups and storing snapshot data using CCI

  You can use CCI raidcom commands to create a consistency or snapshot group and to split pairs to store the snapshot data for the group.

Related Tasks

• Creating Thin Image pairs and defining them in snapshot or consistency groups using CCI

  You can create pairs and define the pairs in a snapshot group or in a consistency group. Define pairs to consistency groups to perform pair tasks on all of the pairs within the group. This task describes how to do this using CCI.

• Removing Thin Image snapshot groups

  You can remove snapshot groups by deleting all of the pairs in the group. Remove snapshot groups before performing the next pair task.

Related References

• Pair tasks using CCI or Device Manager - Storage Navigator

  You can use CCI as well as Device Manager - Storage Navigator (HDvM - SN) to perform pair tasks. When you use CCI, perform tasks by running an existing command for pair tasks or a CCI command.

Parent Topic

• Components of Thin Image

  Thin Image typically consists of several components, including pairs, groups, and software applications. Thin Image requires Dynamic Provisioning, which is used to access data for open-system servers such as UNIX and PC servers in a pool volume through a virtual volume.