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Using Your RAID Enclosure 47
Volume Shadow-Copy Service
The Microsoft Volume Shadow-copy Service (VSS) is a storage management interface for Microsoft
Windows Server
®
2003. VSS enables your storage array to interact with third-party applications that use
the VSS Application Programming Interface. Microsoft VSS is included in the Windows Server 2003
installation.
NOTE: A volume is another term for virtual disk.
VSS attaches to the service and uses it to coordinate the creation of snapshot virtual disks on the storage
array. VSS-initiated snapshot virtual disks can be triggered through backup tools, known as requestors.
The VSS Provider Configuration Tool makes available the following configuration options:
•
Snapshot Repository Virtual Disk Properties
— This section contains a drop-down list for the RAID
level and a field for entering source virtual disk capacity percentage for snapshot repositories.
•
Snapshot Repository Virtual Disk Location
— This section contains a list of preferences for the
location of the snapshot repository virtual disk. These preferences are honored whenever conditions
permit.
The Microsoft VSS installer service for storage provisioning is available on the MD3000 Resource CD in
the \windows\VDS_VSS directory.
Storage Management VSS Hardware Provider Tips:
• The number of snapshot virtual disks that can be created using a single snapshot set varies with the I/O
load on the RAID controller modules. Under little or no I/O load, the number of virtual disks in a
snapshot set should be limited to eight. Under high I/O loads, the limit should be three.
• The snapshot virtual disks created in the storage management software are differential snapshots. Plex
snapshots are not supported.
• Virtual disks to be used as source virtual disks for VSS snapshots should have names no longer than 16
characters. The VSS hardware provider uses the base virtual disk name as a prefix for the snapshot and
repository virtual disk names. The resulting snapshot and repository names will be too long if the
source virtual disk name exceeds 16 characters.
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.