Administrator Guide

Advanced features

The RAID enclosure supports several advanced features:

• Virtual Disk Snapshots

• Virtual Disk Copy

NOTE: The premium features listed must be enabled separately. If you have purchased these features, an activation

card is supplied that contains instructions for enabling this functionality.

Types of snapshot functionality supported

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.

Snapshot images can be created manually or automatically by establishing a schedule that defines the date and time you want to create

the snapshot image. The following objects can be included in a snapshot image:

• Standard virtual disks

• Thin provisioned virtual disks

• Consistency groups

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.

Virtual disk copy

Virtual disk copy is a premium feature you can use to:

• Back up data.

• Copy data from disk groups that use smaller-capacity physical disks to disk groups using greater capacity physical disks.

• Restore snapshot virtual disk data to the source virtual disk.

Virtual disk copy generates a full copy of data from the source virtual disk to the target virtual disk in a storage array.

• Source virtual disk—When you create a virtual disk copy, a copy pair consisting of a source virtual disk and a target virtual disk is

created on the same storage array. When a virtual disk copy is started, data from the source virtual disk is copied completely to the

target virtual disk.

• Target virtual disk—When you start a virtual disk copy, the target virtual disk maintains a copy of the data from the source virtual disk.

You can choose whether to use an existing virtual disk or create a new virtual disk as the target virtual disk. If you choose an existing

virtual disk as the target, all data on the target is overwritten. A target virtual disk can be a standard virtual disk or the source virtual

disk of a failed or disabled snapshot virtual disk.

NOTE: The target virtual disk capacity must be equal to or greater than the source virtual disk capacity.

When you begin the disk copy process, you must define the rate at which the copy is completed. Giving the copy process top priority

slightly impacts I/O performance, while giving it lowest priority makes the copy process longer to complete. You can modify the copy

priority while the disk copy is in progress.

About your MD Series storage array