Help to understand why a so big backup file

[rct]

Hello,

I had a filer VM which has been growing to a point where we couldn't handle the size of backup as we wanted.
We made some clean up to get to what we could handle but the backup was always the same size (because veeam doesn't know that files were erased).
I planned to create another vm disk where I rsynced the data but the backup was bigger... I don't understand why. Could you help me understand that ?

Some more informations:

Initial state
Filer VM with 4 disks stored in an iSCSI storage:
1. system (size 20GB)
2. data1 (size 2TB)
3. data2 (size 2TB)
4. data3 (size 500GB)
The full backup was 3.9TB

I have rsynced the content of the 3 data disks to another disk (5TB) stored in an NFS storage and configured the backup job to exclude disks 2, 3 and 4 from backup.
The full backup is now 6.11TB but the real data written into the disks is only 3.2TB.

My Backup job is configured as a synthetic full.

Any ideas to explain that?

Thank you.

[veremin]

The full backup is now 6.11TB but the real data written into the disks is only 3.2TB.

Can you elaborate on what full backup is meant? The full of the job you've excluded the disk from or the full backup of the newly-created job that has as its source VM to which you synced data?

[rct]

The newly created disk is on the same VM so there is only one backup job.
The week 1 run of the job backuped all the 4 disks (system and data1/2/3).
The week 2 run of the job backuped 2 disks (system and the newly add 5TB disk that we will call data4).

[foggy]

You need to perform an active full to create a new VBK file and reclaim unused space. When some data is excluded from the job, backup file blocks are just marked as free and can be reused by new data, however the file itself cannot shrink in size (file systems do not support that). Active full creates a new backup file by grabbing only actual data from the original VM, so the resulting VBK will be much smaller - while old VBK will be removed by retention eventually.

[rct]

Ok thank you for your answer I will try to do that.