Dell MD3620I, MD3600I owner manual Snapshot Virtual Disks, Snapshot Repository Virtual Disk

Snapshot Virtual Disks

A snapshot is a point-in-time image of a virtual disk. The snapshot provides an image of the virtual disk at the time the snapshot was created. You create a snapshot so that an application (for example, a backup application) can access the snapshot and read the data while the source virtual disk remains online and user-accessible. When the backup is completed, the snapshot virtual disk is no longer needed. You can create up to four snapshots per virtual disk.

Snapshots are used to recover previous versions of files that have changed since the snapshot was taken. Snapshots are implemented using a copy on write algorithm, which makes a backup copy of data the instant a write occurs to the virtual disk. Data on a virtual disk is copied to the snapshot repository before it is modified. Snapshots are instantaneous and take up less overhead than a full physical copy process.

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.

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.

CAUTION: Before using the Snapshot Virtual Disks Premium Feature in a Windows Clustered configuration, you must map the snapshot virtual disk to the cluster node that owns the source virtual disk. This ensures that the cluster nodes correctly recognize the snapshot virtual disk.

Mapping the snapshot virtual disk to the node that does not own the source virtual disk before the snapshot enabling process is completed can result in the operating system misidentifying the snapshot virtual disk. This can result in data loss or an inaccessible snapshot.

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Planning: MD3600i Series Storage Array Terms and Concepts