How much space should I allocate for the File Store?

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Applies To: System Center Data Protection Manager 2007

The space required for DPM System Recovery Tool’s File Store depends on the following conditions:

  • The number of systems scheduled for recovery points.

  • The recovery sets specified for the recovery points.

  • The number and size of applications installed on the protected clients.

  • The version of Windows installed on the protected client computer.

  • The service pack of Windows installed on the protected client.

  • The user files and documents on the protected client, if the specified recovery sets include them.

The two predefined recovery sets (Disk Layout and System Volume) vary in the amount of space they require and the growth rate.

The DPM System Recovery Tool File Store manages space efficiently by storing only one copy of any file with a unique content address computed by a 128-bit SHA-1 cryptographic algorithm. So clients that contain a large number of identical files will use less File Store space than clients that contain a large number of different files.

For the System recovery set, protected clients tend to contain a large number of identical files. This allows for more efficient storage space utilization.

The number and size of application installed on each client, and the number of identical applications among clients, will determine the space required to create recovery points.

Space requirements for customized recovery sets (created with the Recovery Set Editor) will depend on the user-defined selection of files and settings.

The recommended approach for determining the required storage space is to derive it from observing DPM System Recovery Tool in your environment over an initial test period:

  1. When you first install DPM System Recovery Tool, do not specify a limit for the File Store size and do not set a limit on the number of days for recovery points to be retained.  

  2. Schedule a set of systems and let DPM System Recovery Tool create recovery points for these systems on a regular basis for several days to a week.

  3. Note the space require to make the initial recovery point and then compare to the subsequent ones. The first recovery point should require the most space. Subsequent ones recovery points should require less.

  4. Determine the maximum recovery point age that would be acceptable to you when rolling back a system.

  5. Determine the space required to store recovery points for at least one recovery point for each protected client.

Based on the rate of expansion of the File Store for each recovery point schedule after the initial instance, you can determine the space required for at least one recovery point per client and the size that will be exceeded when recovery points have accumulated beyond the age you have determined to be acceptable.  

We recommend that you allow sufficient space for the File Store to contain at least one recovery point per client, plus space for several incremental recovery points within your specified limit on recovery point age.