Retention for Veeam o365 issue?

[Kirmis]

Hello!

I would like your feedback about the retention for Veeam o365 backup.
The goal is through retention to achieve some storage savings from our Backup Repository.

So, I make a simple test is a demo o365 environment to see if its actually works:
- Backup for all Organization / All o365 services for 20 users.
- Configure a Local Storage Repository.
- Set Retention Policy only to 5 days (Snapshot-based retention).

In the first few backups the Backup Repository Size was around 2.3 GB.
After 3-4 days I uploaded an ISO (5.17 GB) to OneDrive of one user.
So, after next backup the Backup Repository Size increased up to 5.21 GB (which is normal).

After this backup job, I deleted this ISO file (also from the OneDrive recycle bin) and I was waiting for 5 days to see if the Backup Repository Size will go again down to ~2.3 GB.

*Here is the interesting part*

After the 5 days I can see from Storage Consumption Report that the Backup Repository Size goes down to 2.3 GB (from 5.21 GB), so I thought that is actually all working fine!
https://imgur.com/EFVAKZP

But its not! ! !


Unfortunately, from file Explorer I can see that the the Backup Repository directory is still over 7 GB ! ! !
https://imgur.com/uNqFRcY

So, Im missing something or the retention for o365 is actually not working ???!

I also upload the full Consumption Report to check!
https://www.udrop.com/shared/k6av4iwnoj ... zo1gz5aln4


Please for your feedback,
Nikos

[Mildur]

Hi Nikos

This is expected behavior and not an issue.
You are using block based backup repository (windows disk mit *.adb files).
On block based repositories, the backup is stored in database files and this files will never shrink by their own.
After the retention removes data from the backup, the space inside this database files can be reused by new backups.

Already discussed here. I will probably merge this topic with the other one.

Thanks
Fabian

[Kirmis]

Dear Fabian,

Thanks for your instant reply!

So, from what I understanding, the Disk Space in Backup Repository directory is going to remain to 7.68 GB, until new backup data "fill" this capacity.

Is that right ?

[Mildur]

Yes. It should.
Just consider, that there is always a chance that the storage space will grow compared to the 7.68 GB, even if there is still space available when you use such small test sizes.

Thanks
Fabian

[Kirmis]

This is clear!
One last thing, same behavior will be also if the Repository is an Azure Blob Storage?

Thanks once again

[Mildur]

You're welcome.
In Azure Blob the backup format is different. We store the backups as objects instead of a single database file for each year.
If the retention needs to delete items from the backup, we just can remove the outdated objects in the Azure Blob and the used storage gets smaller.

VB365 - Object Storage Structure