Clarification around modifying retention - days

[godfreyatlast]

Hello,

Needing some help with understanding changing retention when Backup Job is set to Days (not restore points).

In my VBR 11a test lab I created a Backup Job configured as:
-Forward INC
-running multiple times a day, synth full everyday (my attempt at simulating a weeks backups since I can't manually run a synth)
-per vm repo
-7 days retention.

Testing Steps:
1) I ran the above job for the first time.
2) Ran a full.
3) Ran a few Incrementals.
4) I then changed the retention to 1 days
5) Ran an Incremental (1 day retention)
6) Paused for 24 hours.

7) Today, more than 24 hours later from yesterdays runs, I ran a Synthetic Full.
8) Then ran a few Incrementals

Results:
I see restore points for all the jobs that ran yesterday (both the runs at 7 day & 1 day retention)
I also see the restore points for todays Synth Full & Inc
So far no backups have been deleted, even though the Job retention is currently at 1 days and are more than 24 hours past. ...even the Inc ran in step 5 with 1 day retention still remains which should have been out of retention by todays runs.

To be clear, I think this is a very good outcome as you wouldn't want an admin making a mistake by setting the retention this low and before the accident is caught all your past backups being deleted.

I didn't know what to expect with this testing because I haven't been able to find as much indepth information on "days" retention (a lot more on "restore points"), and I read every page with the word retention in the manual I could find. It seems if I want to modify my retention going forward it's as simple as updating the backup policy. But how would I change (increase or decrease) the retention on exsisting backups? Also, whatever the answer is would it be the same process if I wanted to change exsisting GFS backups as well?

Thanks for any light you can provide!

[Mildur]

Hi James

I hope I get your situation right.
You configured 1 day of retention, but you see more days of restore point as you expect.

If you set the daily retention policy, veeam will always keep the last three successful restore points. That‘s a protection against „having no backups at all for configured vms“.
Imagine you have an issue with the backup job. After three days, veeam would delete the last healthy restore points. Not a good idea

That would explain why you can see yesterdays Full (RP1 to keep) and 1 incremental (RP2 to keep).
And the oldest chain of the 1 Full and 6-7 increments are still there, because the last increment of this backup chain (RP3 to keep) cannot be removed until you have three restore points outside this chain.

This behaviour is documented in the guide.

Mind the following for the daily retention policy:
The minimum number of retained restore points is 3. This number does not depend on the number of days set in the retention policy. For example, the retention policy is set to 5 days. You launch the job after it was stopped for 10 days. Normally, Veeam Backup & Replication would delete all previous restore points. However, due to the minimum number of retained restore points, you will still have at least 3 restore points: the newly created restore point and the two previous ones.
You can change the minimum number of retained restore points with a registry key. For more information, contact Veeam Customer Support.

Decreasing the retention for gfs and short term retention will work, just keep this 3 RPs rule in mind.

There is another thing to notice. Veeam adds +1 day to your retention policy and applies the retention after N+1 days are passed. In your case, that could also extend the retention until the third day, if you have configured 1 day.

[godfreyatlast]

Thanks for the explaination @Mildur

I had read that page but guess it didn't sink in with those extra protections. Now that I have a 3rd day of backups I see day 1's backups have expired out of retention, so things are working as they should! I should have waited another day before posting