Space used by files on new backup server

[pls]

We are in the middle of moving Veeam to a new physical server. Current server is Server 2019 64K blocks and using ReFS. New server is the same. I am using robocopy to move the local backup files from the old server to the new server. The used space on the old server is 7.62TB. The used space on the new server is 15.87TB. What might cause the copied files to take up twice as much space on the new server?
Thanks

[foggy]

Hi Phil, ReFS block cloning works on a per volume basis and space savings cannot be simply copied from one volume to another - data is being "rehydrated".

[Mildur]

You could use a copy tool, which works on the disk block level. I have never used something like that, but i should preserve the disk savings from the refs block cloning api.

[pls]

After the migration and we start using the new server and new synthetic fulls are created and the existing files age out will I get my space back? I will admit ReFS block cloning is not something I know a lot about.
Thanks

[Mildur]

After the migration and we start using the new server and new synthetic fulls are created and the existing files age out will I get my space back?

If you have mapped backup job to this moved files, you will need todo a active full or backup file compact operation to use refs Block Cloning. If you don‘t do that, you will not be able to use Fast Clone again and every synthetic full will use the complete space on disk.

The old backup files will be deleted according to your retention policy if you have the backup jobs mapped to the moved files.

If you have created new jobs, backups and FastClone will work without any interaction. Old restore Points needs to be removed manually.

https://helpcenter.veeam.com/docs/backu ... ml?ver=110

After you have enabled Fast Clone for existing repositories as described in the previous paragraph or have moved backup chains to backup repositories with Fast Clone support, you must create active full backups for backup chains stored in / moved to the repositories to activate Fast Clone. You can also schedule the backup file compact operation instead of performing active full backup.

[pls]

Thanks, I missed the part about fast clone. That looks like pretty important step.