Best practice for calculating the storage space requirements for System Recovery.

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Best practice for calculating the storage space requirements for System Recovery.


This document is to address what to consider when calculating the storage space needed by a System Recovery agent.

Backup method.

    When considering storage space, the type of backup method or job to be scheduled by an agent plays a role. For more information on how to define a drive-based backup, please review the appropriate article in the related document section below.

    A baseline or an Independent recovery point job schedule creates:
      - A complete, independently recoverable copy of the drives selected at the time the backup job schedule was made.

      A backup schedule of just baseline or independent recovery points requires more storage space than a schedule that utilizes incremental recovery points.

      Incremental recovery points are
        - Dependent on the last baseline image that was made.
        - Not an available option for Independent recovery point based backup schedules.
        - Files (*.iv2i) that contain only the changes that were made since the previous baseline recovery point, or last incremental, of drives selected within the backup job schedule.  

        Incremental recovery points are often faster to create than its baseline recovery point and take up less storage space.

        A job that utilizes incremental recovery points is called a Recovery point set and is the recommend backup method for the System Recovery product. The remaining portion of this document will consider storage needs based upon this backup method.

        Recovery point Set 

        A recovery point set is both a backup method and the abstract used to define a baseline and all the incremental recovery point images up to but not including the next baseline image for the drives of a backup schedule.

        An important point to be aware of is that system recovery does not overwrite a recovery point set. It creates an additional backup, then removes the oldest one according to your retention rules.

        System recovery requires enough disk space for N +1 recovery points on the backup destination (n = the number of recovery points you wish to keep). The oldest recovery point set will not be deleted until the +1 recovery point is completed


        • Recovery point set total size = 150 GB
        • Number of recovery point sets to keep = N (N=3 is the default setting)
        • Backup destination space required = 600 GB ((150*N) + (150*1))

        When the fourth (N+1) baseline recovery point is completed, the first Recovery Point Set (the baseline in all its incrementals) will be removed from storage.



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