Laptop User Manual

Configuration: Premium Feature—Snapshot Virtual Disks 143
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Configuration: Premium Feature—
Snapshot Virtual Disks
NOTE: If you ordered this feature, you received a Premium Feature Activation card
shipped in the same box as your Dell PowerVault MD storage array. Follow the
directions on the card to obtain a key file and to enable the feature.
NOTE: The snapshot feature allows up to eight snapshots per LUN and 128 per
array to be present at the same time.
A snapshot virtual disk is a point-in-time image of a virtual disk in a storage
array. It is not an actual virtual disk containing a copy of the original data; It is
a reference to the data that was contained on a virtual disk at a specific time.
A snapshot virtual disk is the logical equivalent of a complete physical copy.
However, you can create a snapshot virtual disk much faster than a physical
copy, using less disk space.
The virtual disk on which the snapshot is based, called the source virtual disk,
must be a standard virtual disk in your storage array. Typically, you create a
snapshot so that an application, such as a backup application, can access the
snapshot and read the data while the source virtual disk remains online and
accessible.
NOTE: No I/O requests are permitted on the source virtual disk while the virtual
disk snapshot is being created.
A snapshot repository virtual disk containing metadata and copy-on-write
data is automatically created when a snapshot virtual disk is created. The only
data stored in the snapshot repository virtual disk is that which has changed
since the time of the snapshot.
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