Dell EMC PowerVault MD 34XX/38XX Series Storage Arrays Administrator's Guide

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Snapshot groups

The purpose of a snapshot group is to create a sequence of snapshot images on a given base virtual disk without impacting performance. You can set up a schedule for a snapshot group to automatically create a snapshot image at a specific time in the future or on a regular basis.

When creating a snapshot group, the following rules apply:

Snapshot groups can be created with or without snapshot images.
Each snapshot image is can be a member of only one snapshot group.
Standard virtual disks and thin virtual disks are the only types of virtual disks that can contain a snapshot group. Non-standard virtual disks, such as snapshot virtual disks, cannot be used for snapshot groups.
The base virtual disk can reside on either a disk group or a disk pool.
Snapshot virtual disks and snapshot groups cannot exist on the same base virtual disk.

A snapshot group uses a repository to save all data for the snapshot images contained in the group. A snapshot image operation uses less disk space than a full physical copy because the data stored in the repository is only the data that has changed since the latest snapshot image.

A snapshot group is created initially with one repository virtual disk. The repository initially contains a small amount of data, then increases over time with subsequent data updates. You can increase the size of the repository by increasing the capacity of the repository, or add virtual disks to the repository.