Information about Data Dedup

Windows server have a function for data deduplication (
is there any downside to have it activated with Urbackup ?

As i understand Urbackup and windows seems to do the same thing (more or less)
but i already have data dedup enable on the storage pool, so i want to be on the safe side.

UrBackup only does file-level dedup and doesn’t dedup the image backups at all, so there is something to gain. Plus it probably gives you better compression than the NTFS compression.

It doesn’t play well together with ReFS and reflinks, though. And you should backup to vhd instead of vhdz (better dedup).

i am on ReFS :-/ so it is better to not do it ?

and thank you, i will disable compression for vhdz if i go foward, waiting for an answer for the reflinks.

If you have large files with small changes during backups or backup to the raw image file format and you run image backups frequently it’ll cause large copy operations which then later have to be deduped away (performance problem + temporary space usage). Reflinks do not work in combination with dedup, so it’ll copy instead of reflink.