ACRONIS Backup & Recovery 10 Advanced Server Virtual Edition User's Guide download pdf (Page 151)

This figure demonstrates that the GFS Example 2 tape rotation scheme is more suitable for the case

than GFS Example 1. The advantages of the GFS Example 2 tape rotation scheme for the analyzed

case are the following:

 it uses 16 tapes instead of 25

 a data recovery task requires one (25%) or two (75%) tapes

 data recovery from a full backup requires only one tape that makes the data recovery from an

incremental or differential backup faster.

GFS Example 3

Imagine the backup plan has the following tape options:

 the Use a separate tape set option is selected

 the Always use a free tape: For each full backup option is selected

 the Always use a free tape: For each incremental backup option is selected

 the Always use a free tape: For each differential backup option is selected.

These options define the tape rotation scheme that is classical for GFS. The figure shows the

beginning of the rotation scheme that uses 8 tapes for daily backups, 6 tapes for weekly backups and

13 tapes for monthly backups (since there are 13 four-week cycles in a year) for the analyzed case.

And one tape is required for the next backup. In total this rotation scheme, combined with the

options requires 28 tapes.

To recover the data only one tape is required for a full backup, two tapes for a differential backup,

and two or three tapes for an incremental backup.

This scheme has the following advantages:

 access to any full backup requires only one tape

 backup deletion frees a tape so it can be reused.

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ACRONIS Backup & Recovery 10 Advanced Server Virtual Edition User's Guide Page 151