Create consistency group

Supported Arrays​

This command applies to an individual DE2000H, DE4000H, DE4000F, DE6000H, or DE6000F storage array.

Roles​

To execute this command on an storage array, you must have the Storage Admin role.

Syntax​

create consistencyGroup userLabel="<var id="GUID-6E49BB58-3330-44C4-9BEC-D8DA2A33C1BB__V1111058" className="keyword varname">consistencyGroupName</var>" 
[repositoryFullPolicy=(failBaseWrites | purgeSnapImages)] 
[repositoryFullLimit=<var id="GUID-6E49BB58-3330-44C4-9BEC-D8DA2A33C1BB__V1438428" className="keyword varname">percentValue</var>] 
[autoDeleteLimit=<var id="GUID-6E49BB58-3330-44C4-9BEC-D8DA2A33C1BB__V1440328" className="keyword varname">numberOfSnapImages</var>] 
[enableSchedule=(TRUE | FALSE)] 
[schedule (immediate | <var id="GUID-6E49BB58-3330-44C4-9BEC-D8DA2A33C1BB__V1320811" className="keyword varname">snapSchedule</var>)] 
[rollbackPriority=(lowest | low | medium | high | highest)]

Parameters​

Notes​

A consistency group is a logical entity that enables you to manage in batch form all of the snapshot images that you add to the collection. The consistency group is a collection of snapshot groups that have mutual consistency requirements or dependencies for their snapshot images. Any snapshot images that you create and use for this collection must be managed in accordance with the consistency dependencies.

You can use any combination of alphanumeric characters, underscore (_), hyphen (-), and pound (#) for the names. Names can have a maximum of 30 characters.

The snapshot images in a consistency group can be deduced based on the existence of a snapshot image within a consistency group. All snapshot images that reside within a consistency group share a common time stamp and sequence number.

An operation on a snapshot image consistency group is treated as a single request, and causes all pending I/O operations to the associated base volume of each member to be drained and suspended before creating the snapshot images. If creation of the snapshot images cannot be completed successfully for all of the consistency group members, the operation fails and has no affect (that is, new snapshot images are not created).

Based on this behavior all members for a consistency group usually have the same number of snapshot images. However, when a new member is added to a consistency group, that new member lacks the snapshot images that were previously created on the established members of the consistency group. The lack of snapshot images is not considered an error condition. Ensuing requests for deletion or rollback of snapshot images that only exist on a subset of the consistency group members will only affect the members for which the specified snapshot images actually exists.

Auto delete​

You can configure each snapshot group to automatically delete its snapshot images to keep the total number of snapshot images in the snapshot group at or below a maximum number of images. When the number of snapshot images in the snapshot group is at the maximum limit, the autoDeleteLimit parameter automatically deletes snapshot images whenever a new snapshot image is created in the snapshot group. The autoDeleteLimit parameter deletes the oldest snapshot images in the snapshot group until the maximum number of images defined with the parameter is met. This has the effect of freeing repository capacity so it can be used to satisfy ongoing copy-on-write requirements for the remaining snapshot images.

Scheduling snapshot images in a consistency group​

The enableSchedule parameter and the schedule parameter provide a way for you to schedule snapshots. Using these parameters, you can schedule snapshots daily, weekly, or monthly (by day or by date). The enableSchedule parameter turns on or turns off the ability to schedule snapshots. When you enable scheduling, you use the schedule parameter to define when you want the snapshots to occur.

This table explains how to use the options for the schedule parameter:

This table explains how to use the timeZone parameter:

The code string for defining a schedule is similar to these examples:

enableSchedule=true schedule startTime=14:27

            

enableSchedule=true schedule scheduleInterval=180

            

enableSchedule=true schedule timeZone=GMT-06:00

            

enableSchedule=true schedule timeZone="America/Chicago"

            

If you also use the scheduleInterval option, the firmware chooses between the timesPerDay option and the scheduleInterval option by selecting the lowest value of the two options. The firmware calculates an integer value for the scheduleInterval option by dividing 1440 by a the scheduleInterval option value that you set. For example, 1440/180 = 8. The firmware then compares the timesPerDay integer value with the calculated scheduleInterval integer value and uses the smaller value.

To remove a schedule, use the delete volume command with the schedule parameter. The delete volume command with the schedule parameter deletes only the schedule, not the snapshot volume.

When performing a rollback in a consistency group, the default operation is to rollback all members of the consistency group. If a rollback cannot be started successfully for all of the members in the consistency group, the rollback fails and has no effect. The snapshot image is not rolled back.