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

The following types of virtual disk snapshot premium feature is supported on the MD storage array:

• Snapshot Virtual Disks using multiple point-in-time (PiT) groups — This feature also supports snapshot groups, snapshot images, and consistency groups.

For more information, see Premium Feature---Snapshot Virtual Disk.

Snapshot virtual disks, snapshot images, and snapshot groups

A snapshot image is a logical image of the content of an associated base virtual disk created at a specific point-in-time. This type of image is not directly readable or writable to a host because the snapshot image is used to save data from the base virtual disk only. To allow the host to access a copy of the data in a snapshot image, you must create a snapshot virtual disk. This snapshot virtual disk contains its own repository, which is used to save subsequent modifications made by the host application to the base virtual disk without affecting the referenced snapshot image.

To create a snapshot image, you must first create a snapshot group and reserve snapshot repository space for the virtual disk. The repository space is based on a percentage of the current virtual disk reserve.

You can delete the oldest snapshot image in a snapshot group either manually or you can automate the process by enabling the Auto-Delete setting for the snapshot group. When a snapshot image is deleted, its definition is removed from the system, and the space occupied by the snapshot image in the repository is released and made available for reuse within the snapshot group.