Tape planning: Example 2
Imagine the case with the following features:
The case defines the line of backups that consists of two sections. The figure below shows the sections at the moment before the first backup will be deleted. In the figure the full, differential and incremental backups are designated as orange, blue and green rectangles respectively.
At the moment some backups are deleted by the Cleanup task. Deletion of the outdated backups painted in dark colors is postponed, as these backups are basic for the actual backups.
As an exact correlation between the tape size and backup’s size is unknown, it is impossible to determine number of the tapes that will be free after the deletion. So the calculation ignores this probability.
Tape set 01 should contain (round up (( F_GB + 4*D_GB + 5*7*I_GB) * CL / T_GB)) tapes to store the backups. Tape set 02 needs (round up (( F_GB + 1*D_GB + 7*I_GB) * CL / T_GB)) tapes. The sum of the calculated values gives the total number of tapes required for the case.