I’m in need of some assistance with setting up a backup retention strategy for our system. Our current requirement is to keep intra-daily backups (which we are taking every two hours) for at least 14 days, followed by at least 8 weeklys, 6 monthly, and 1 yearly backups. However, I’m encountering issues with the correct syntax to achieve this.
My goal is to configure the following:
Keep all backups (taken every two hours) for at least 14 days.
After 14 days, switch to keeping one backup per week for 8 weeks.
Then, keep one backup per month.
And finally, one backup per year.
I tried using the format “17D:1D,8W:1W,1M:1M,1Y:1Y”, but it doesn’t seem to support intra-daily backups. Is there a way to specify hourly or every-two-hour backups in this syntax? Or would I need a different approach to include the 2-hourly backups for the initial 14 days?
Any advice or guidance on how to structure this retention strategy would be greatly appreciated!
Yes, you can keep multiple backups from a single day.
The timing of the individual elements may not work quite the way you’d think. Each time descriptor works backwards from “now”, not from when the prior time descriptor ended but that only creates a small wrinkle in what you’re trying to do. I tried to explain below.
For what you’re trying to do, I think you want:
“14D:U” - for the most recent 14 days keep all backups
“8W:1W” - for the most recent 8 weeks, keep 1 per week (for the most recent 2 weeks, it’s keeping all of them due to the prior rule). If what you really wanted was 1 backup per week for the 8 weeks following the 2 weeks of the first rule, you’d do “10W:1W”.
I’m assuming you want the “1 per month” to go through the remainder of the year. If so, you’d then do:
“12M:1M” - for the most recent 12 months, keep 1 per month (again, prior rules take precedence for the most recent 2 weeks, and 8 weeks respectively)
“U:1Y” - I’m not 100% sure on using “U” on the left of the colon, to be honest. I set it in one of my own policies, but haven’t gotten to the timeframe where it would invoke yet!
All together that would be:
“14D:U,8W:1W,1Y:1M,U:1Y”
or, if you intended the 8 week period to start after the 2 week period:
If no files have changed, Duplicati will not upload a backup set. If the backup data is used to verify that a backup was executed, this option will make Duplicati upload a backupset even if it is empty.
can also be set, if you’re trying to achieve a certain “look”. The second sentence seems a bit off, but is probably thinking about an empty incremental backup, to use more traditional terminology.
All of Duplicati’s backups have a full list of the files, but deduplication only uploads the changes.
Incremental backups
Duplicati performs a full backup initially. Afterwards, Duplicati updates the initial backup by adding the changed data only. That means, if only tiny parts of a huge file have changed, only those tiny parts are added to the backup. This saves time and space and the backup size usually grows slowly.
Presumably on your Restore menu, you didn’t see the backup whose log you showed, because nothing changed, therefore there was little point to spend the resources on an identical version simply to show a different date. If specific appearance is important, you could turn the option on.
