Using Shadow Copies of Shared Folders in a server cluster

Shadow Copies of Shared Folders provides point-in-time copies of files that are located on shared resources, such as a file server. You can use Shadow Copies of Shared Folders as part of your overall disaster recovery strategy to quickly recover files that were accidentally deleted or overwritten, as well as to compare different versions of files. However, there are several important considerations to keep in mind if you want to use Shadow Copies of Shared Folders on a cluster disk:

• Cluster-managed shadow copies can only be created in a single quorum device cluster on a disk with a Physical Disk resource. In a single node cluster or majority node set cluster without a shared cluster disk, shadow copies can only be created and managed locally.
• The recurring scheduled task that generates volume shadow copies must run on the same node that currently owns the storage volume.
• The cluster resource that manages the scheduled task must be able to fail over with the Physical Disk resource that manages the storage volume.

The Volume Shadow Copy Service Task resource type can be used to manage shadow copies in a server cluster. The Volume Shadow Copy Service Task resource used in this way has a required dependency on the Physical Disk resource.

For more information on the Volume Shadow Copy Service Task resource type, see Volume Shadow Copy Service Task resource type.

Best practices for using shadow copies in a cluster

• To improve server performance, use different disks for the shadow copy volume and the storage volume.

  Note

  • You cannot create storage volume associations between distinct volumes on a disk managed by a single Physical Disk resource.
• If you have multiple shadow copy volumes, use a single, separate disk for the storage volume.
• Do not enable shadow copies in a deployed cluster. When you enable shadow copies, the shadow copy volumes (as well as all resources that directly or indirectly depend on the disk) go offline for a brief period while the resource dependencies are created. The shadow copy volumes are not accessible to applications and users while they are offline.
• Enable shadow copies after you have created your cluster. If you enable shadow copies before clustering your servers, you must disable, then reenable, shadow copies.

  Note

  • If you cluster a disk containing a previously-created shadow copy, the shadow copy may stop functioning once that disk's Physical Disk resource fails over.

Using Cluster Administrator or cluster.exe to manage shadow copies

Important

• Using Cluster Administrator or cluster.exe to completely configure and manage shadow copies in a cluster is not a supported scenario. The only supported scenario for configuring shadow copies in a cluster is described in To enable Shadow Copies of Shared Folders in a cluster.

For more information on using Cluster Administrator to create a Volume Shadow Copy Service Task resource, see Checklist: Installing a Volume Shadow Copy Service Task resource.

For more information on using cluster.exe to create a Volume Shadow Copy Service Task resource, see Cluster resource.

Enabling shadow copies on a cluster node

When you enable shadow copies on a cluster node (for example, by using the Configure Shadow Copy user interface through the Computer Management MMC ), a Volume Shadow Copy Service Task resource and a scheduled task for creating that shadow copy are automatically generated and configured. You do not need to explicity create the Volume Shadow Copy Service Task resource using Cluster Administrator or cluster.exe. In addition, the Configure Shadow Copy user interface automatically sets up the required resource dependencies. The default properties of the scheduled task and Volume Shadow Copy Service Task resource are described in the table below. For more information, see To enable Shadow Copies of Shared Folders in a cluster.