54 Planning: MD3200i Series Storage Array Terms and Concepts
You can copy data from a virtual disk in one of 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 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 available on the MD3200i 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
controller module owner of a virtual disk after it is created. If a host is only
connected to only one RAID controller module, the preferred owner must
manually be assigned to the RAID controller module the host can access.
Ownership of a virtual disk is moved from the preferred controller to the
secondary controller (also called the alternate controller) when the preferred
controller is:
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