New retention policy deletes old backups in a smart way

[JonMikelV]

The in-GUI docs say:

Enter a retention strategy manually. Placeholders are D/W/Y for days/weeks/years and U for unlimited. The syntax is: 7D:1D,4W:1W,36M:1M. This example keeps one backup for each of the next 7 days, one for each of the next 4 weeks, and one for each of the next 36 months. This can also be written as 1W:1D,1M:1W,3Y:1M.

But here’s some more detail:

Retention config setup (stacking arguments with same timeframe?)

Yes, it’s essentially for X [time] keep one backup every X [time] With support for s - second m - minute h - hour D - day W - week M - month Y - year One “different” option isn’t really a time, it’s more of a concept U:1D - for unlimited time keep one backup for every 1 day 1D:U - for 1 day keep unlimited backups It’s also worth noting the time-frames are somewhat fuzzy, but they do not accumulate. So even though you keep one every 8 hours you don’t have to backup exactly at multiples of 8…

Note that it’s important to understand that these are timeframes, not specific periods. So if you say 1W that means 1 week between backup versions NOT any specific Mon-Sun time period. (More specifically, the timeframes are converted to seconds and that’s what’s used when comparing how far apart two backup versions are.)