Snapshot Repository Virtual Disk; Virtual Disk Copy - Dell PowerVault MD3000 Hardware Owner's Manual

Snapshot Repository Virtual Disk

When you create a snapshot virtual disk, it automatically creates a snapshot repository virtual disk. A
snapshot repository is a virtual disk created in the storage array as a resource for a snapshot virtual disk. A
snapshot repository virtual disk contains snapshot virtual disk metadata and copy-on-write data for a
particular snapshot virtual disk. The repository supports one snapshot only.
Because the only data physically stored in the snapshot repository virtual disk is that which has changed
since the time of the snapshot, the snapshot technology uses less disk space than a full physical copy.
You cannot select a snapshot repository virtual disk as a source virtual disk or as a target virtual disk in a
virtual disk copy. If you select a Snapshot 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.

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, or 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 will slightly impact I/O performance, while giving it lowest priority will
make the copy process take longer to complete. You can modify the copy priority while the disk copy is in
progress.
You can find more details on using the virtual disk copy feature in the MD Storage Manager User's Guide.
Virtual Disk Recovery
You can use the Edit host-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, then map the
backup virtual disk to the same host.
Ensure that you record the LUN used to provide access to the source virtual disk. You will need this
information when you define a host-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.
39
Using Your RAID Enclosure