Dell POWERVAULT MD3600I - Manual (Page 30)

• 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. For more information,
see the online help.
Virtual Disk Recovery
You can use the Edit host server-to-virtual disk mappings feature to recover data from the backup virtual disk. This
functionality enables you to unmap the original source virtual disk from its host server, then map the backup virtual disk
to the same host server.
Ensure that you record the LUN used to provide access to the source virtual disk. You need this information when you
define a host server-to-virtual disk mapping for the target (backup) virtual disk. Also, be sure to stop all I/O activity to the
source virtual disk before beginning the virtual disk recovery procedure.
Using Snapshot And Virtual Disk Copy Together
You can use the Snapshot Virtual Disk or Snapshot Virtual Disk (Legacy) 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 in one of the two ways:
• By taking a point-in-time snapshot of the data
• By copying the data to another virtual disk using a virtual disk copy
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 to 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 the 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 MD Series storage arrays resource DVD.
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