Using snapshot and disk copy together, Multi-path software, Preferred and alternate controllers and paths – Dell POWERVAULT MD3620I User Manual

Page 54: Preferred and alternate controllers, And paths

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Planning: MD3600i Series Storage Array Terms and Concepts

Using Snapshot and Disk Copy Together

You can use the Snapshot Virtual Disk and Virtual Disk Copy premium

features together to back up data on the same storage array, or to restore the

data on the snapshot virtual disk to its original source virtual disk.
You can copy data from a virtual disk by:

• Taking a point-in-time snapshot of the data (online)
• Copying the data to another virtual disk using a virtual disk copy (offline)

You can select a snapshot virtual disk as the source virtual disk for a virtual

disk copy. This configuration is one of the best ways you can apply the

snapshot virtual disk feature, since it enables complete backups without any

impact on the storage array I/O.
You cannot use a snapshot repository virtual disk as a source virtual disk or as

a target virtual disk in a virtual disk copy. If you select the source virtual disk

as the target virtual disk of a virtual disk copy, you must disable all snapshot

virtual disks associated with the source virtual disk.

Multi-Path Software

Multi-path software (also referred to as the failover driver) is a software

resident on the host server that provides management of the redundant data

path between the host server and the storage array. For the multi-path

software to correctly manage a redundant path, the configuration must have

redundant iSCSI connections and cabling.
The multi-path software identifies the existence of multiple paths to a virtual

disk and establishes a preferred path to that disk. If any component in the

preferred path fails, the multi-path software automatically re-routes I/O

requests to the alternate path so that the storage array continues to operate

without interruption.

NOTE:

Multi-path software is available on the MD3600i Series resource media.

Preferred and Alternate Controllers and Paths

A preferred controller is a RAID controller module designated as the owner of

a virtual disk or disk group. The preferred controller is automatically selected

by MDSM when a virtual disk is created. You can change the preferred RAID

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