Ekaterina, Can I Delete Older Differential Backup Files Without Losing Ability To Restore Later Ones or the Full Backup?

Hi! 

So, as every differential backup depends on a base full backup only, it will be possible to restore the data from the remaining diffs, they are not tied to each other. However, if you remove some backups manually via Windows Explorer, there will be inconsistency in the metadata files that contain information about the actual backup archives lying in the vault. Perhaps it would be better to move the whole chain to another location and start a new archive, where the retention rules will be adjusted to better suit the location size. 

Dear Ekaterina,

Thank you for your reply.

I was under the impression that at the conclusion of every backup, the Acronis Backup program searches the entire disk where the backups are stored and updates all meta data for everything it finds.

I thought this because after I complete any kind of backup, the disk where they are stored has activity for about 20 minutes afterward and when I have looked at the directories to make sure none of my files got deleted, I find what appear to be meta data files with dates and times corresponding to the last backup ever done and stored to that disk.

If it is not the meta data files being updated, what is actually happening in that 20 minutes and why are the file dates and times set to the date and time of the last backup ever done and stored to the disk?

Also, if I delete the unneeded files while running inside the Acronis program, for example using the A43 tool, will the metadata files be updated?

Thank you for your help.

Bump

Hi! 

You can either delete unwanted backups via Acronis Backup UI or by using this command: https://www.acronis.com/en-us/support/documentation/AcronisBackup_11.7/…

The metadata .XML file should be updated automatically. Otherwise, you can press the "Refresh" button at the right top of a vault with this archive to refresh the metada file.

If you see that medata still not updated, you can open the .XML metafile and delete data blocks from there with descriptions of the unwanted differential archive slices (you can identify those by creation date, backup filename etc.). However, please save a copy of this file before editing it. 

Dear Maria,

Thank you for replying to my post.

I will try using the Acronis user interface to delete a differential backup fileset of lesser importance, just in case something goes wrong and the entire archive gets deleted or corrupted by mistake or glitch.

I'll post back with my experience.

TTYL

Hi! 

You may run a new full backup and store it at another location while updating your backup archive so that you have a new backup at hand if anything goes wrong.

I went into Browse Vaults and confirmed that I had a backup consisting of a Full Backup and three Differentials.

The Full Backup is #1.
The Differentials are numbered #2, #3, and #4.

I deleted Backup #2.
I got an error message indicating the process failed.
Backup #2 was still listed in the Browse Vault listing for the Archive (folder).

I rebooted and went into Windows 7 Pro 64.
I used Windows Explorer and looked at the folder.
The files I wanted to delete actually were deleted.

I rebooted into Windows PE 3.0 and went to Browse Vaults again.
Backup #2 still was listed.

I did a Validation on Backup #4.
It completed successfully.
But in Browse Vaults Backup #2 was still listed.

I tried to Validate Backup #2.
The process failed almost immediately.

I tried to Validate the entire Archive (folder).
It failed when it got to Backup #2.

Then I did a New Differential Backup.
It completed successfully.
At the end after Validation completed, the disk was very active for quite a while.
I noticed this always seems to happen at the conclusion of Validation after a Backup.
I waited till the disk calmed down, (no more noise and just an occasionaly flicker of the activity LED).
I went into Browse Vaults and saw that the numbering had been re-ordered.
Backup #3 was now Backup #2.
Backup #4 was now Backup #3.
The new Differential was now Backup #4.

Just to be safe.
I created a new folder (Archive) and did a Full Backup.
It completed and Validated successfully.

So here is the takeaway...

If you want to delete an intermediate Differential to save space.
Go into Browse Vaults.
Highlight the Differential you want to Delete.
Click the "X".
You will get an error message, but it really does delete the files.
Next, run your New Differential Backup process.
After the Validation completes, the disk will be active for quite a while.
When it quiets down, you can look in Browse Vaults and you will see that the Backup Numbers have re-ordered themselves.

I hope a future update of 11.7 actually forces the refresh when you delete and no error message.
I hope that version 12.5 does all this in a better way.

And I Hope this information helps the next person.