Hi there !
Just a simple question, I configured my backup to use smart retention policy, so from what I’ve understood, it should keep:
1 backup per day for the last 7 days (so 7 versions in the last 7 days)
1 backup per week for 4 last week (so after these 7 versions, 4 versions)
1 backup per month for 12 last month
1 backup per year
Am I correct ?
Because when I look on my duplicati instance, I set the policy here : 1W:1D,4W:1W,12M:1M
But here is my history if I try to restore files:
On the last week, it should have keep one file per day, but the 09/12 is missing.
If I look into the logs, I can see the 09/12 the backup operation has been successfully achieved. The day after, the 10/12, I can see it deleted the version of the 09/12…I can’t understand why !
Can you help ?
The backup is programmed at 3am each day, and I double checked that the time is correct.
This part isn’t in the GUI description (where is it from?), but you could add ,U:1Y if you want it.
Some may say 1 backup per year would be “smarter”, but I don’t think that’s the way it is now:
Over time backups will be deleted automatically. There will remain one backup for each of the last 7 days, each of the last 4 weeks, each of the last 12 months.
How did you check time of backup? 1 day is an interval (not calendar-based) down to second.
Sometimes backup starts vary a bit, so 1W:1D,4W:1W,12M:1M for daily occasionally misses.
You could test a custom retention of 1W:23h,4W:1W,12M:1M to see if it avoids clipped dailies.
The Dec 9 backup is deleted if it is less than 86400 (24 * 60 * 60) seconds after Dec 8 backup.
Dec 9 when first made is exempt from deletion just after, but it loses the exemption on Dec 10.
If you kept a log-file log with at least information level, you would see Backups to consider.
Did all start at exactly 3:00:00 AM, or are any a bit late? Maybe some grace time could be used.
Indeed I missed the proper definition ! I’m okay with it. Thanks for the clarification.
Ok, I start to understand better ! When I say I checked the time, I connect to the container where Duplicati is hosted and I issue “date” command. So the timezone is correct for example. I also checked on the backup logs in Duplicati (it indicates which version is deleted).
I’m not sure which time I should take in order to do calculations but I guess it’s working as intended.
So OK, I’ll try with 23h instead of 1D, I guess it should work fine if the backup take less than 1hour, which should be the case.