Shadow Copies

Published : April 8, 2005 | Updated : August 17, 2005

To support rapid recovery of protected data, DPM leverages Volume Shadow Copy Service (VSS) technology to create shadow copies of the replica, which are stored on the DPM server. Shadow copies are point-in-time snapshots of the replicas that the DPM server stores for protected volumes. Users access the shadow copies to recover previous versions of protected data. Figure 1.8 shows the relationship between shadow copies and the replica for a protected volume.

Figure 1.8   At scheduled times, a shadow copy is created from the replica

DPM can store a maximum of 64 shadow copies for each volume in a protection group. When storage area limits have been reached and a new shadow copy is created, the oldest shadow copy is automatically deleted and cannot be restored.

You can achieve your recovery goals by carefully scheduling shadow copies for protection groups. The protection schedule provides a full range of options, from eight days to 64 weeks of data protection, with a maximum data loss ranging from one hour to one week.