MSSQL Empty Space

[tom11011]

Hi Group,

I want to re-enforce my understanding of what is backed up.

The team has been tasked with removing data from some rather large MSSQL databases that Veeam regularly backs up and replicates.

As an example, what will happen to backup size when a 1TB database has 500gigs of data removed from it, but is not shrunk? Obviously the file size in windows doesn't change, but what happens at the block level? I know Veeam will only backup what blocks have changed, but how might that space be reclaimed in the Veeam repository?

Thank you!

[HannesK]

Hello,
space on the repository is reclaimed when retention is applied. One might argument, that "Defragment and compact full backup file" is also space reclamation - up to you, how to define it.

That behavior is independent from what is backed up. Content of existing backup files always stays the same (that's the purpose of a backup in general)

Best regards,
Hannes

[micoolpaul]

Hi,

So, MSSQL will still claim the space on disk, and won't zero the blocks, which means that Veeam still needs to process it.

You should shrink the database to allow for your new dataset + required growth to prevent frequent database growth stuns, once this is done the blocks are properly deallocated and marked as free which should allow Veeam to space save further on the backups.