Advanced retention policy (legacy)

OS

All

Software

5.5 - 6.29 Pro Backup

Technology

Advanced retention policy

Explanation

How does the "Remove overlap" option under the advanced retention settings work?

In general the sequence is the following:
Daily snapshots followed by a weekly or a monthly snapshot etc... will be removed.
Weekly snapshots followed by a monthly or quarterly snapshot etc... will be removed.
and so on.

Example:
Assuming today is 16th of January 2014 and the advanced retention policy is as follows:
- Daily: keep 7 days
- Weekly: keep 4 weeks (this task will be executed on Saturday)
- Monthly: keep 3 months (This task will be executed on the 1st of the month)

When the remove overlap option is disabled:
A total of 14 snapshots (7+4+3) will be saved on the server because:
(Daily): 10Jan14, 11Jan14, 12Jan14, 13Jan14, 14Jan14, 15Jan14, 16Jan14
(Weekly): 24Dec13, 31Dec13, 7Jan14, 14Jan14
(Monthly): 1Nov13, 1Dec13, 1Jan14

When the remove overlap function is enabled:
Only the following snapshots will be saved: 1Nov13, 1Dec13, 1Jan14, 14Jan14, 15Jan14, 16Jan14.

Because the weekly policy overwrites the daily policy the snapshots 10Jan14, 11Jan14, 12Jan14 and 13Jan14 will be removed. And the monthly policy overwrites the weekly policy removed the snapshots 24Dec13, 31Dec13 and 7Jan14.