Backup unexpectedly deleted with custom retention plan and scheduled backup #3987
looks like relevant open issue. Fixes come from issues (limited by volunteers). Forum can’t track.
By linking to the issue, it updates, so may raise visibility. Feel free to read through and add a note.
Switching to calendar base is messy because interval can be non-calendar things, e.g. seconds.
There are also culture-varying definitions of even what it means to be per week. Time is just time.
This is likely a common and visible case, based on reports. There are few on weeks and months.
The fix may be a combination of documentation (manual, code) and somehow allowing tolerance.
If you look at the issue, you can see precedent for allowing tolerance, but it’s not done for this use.
Simplest “fix” for this particular case might be either a fixed allowance, or tweak “smart retention”.
Could you look at your June 27 backup log to see what second it started at? They’re usually close.
That’s not always good enough when the backup schedule and the interval are precisely identical.
is “Smart backup retention”. It could possibly be altered a bit, as was suggested for custom values.
Maybe take a few seconds off (how far off was yours?). Or just give a fixed tolerance for them all…
That will solve some problems of colliding values for typical use. Documentation can cover experts.