Decompress backup file data blocks on XFS?

[Anguel]

Hi,

I am setting up a hardended linux repo with XFS and want to send backup copy jobs to it. As XFS seems to feature deduplication, now I wonder if I should enable or disable "Decompress backup file data blocks before storing" in the repo advanced settings.
FYI, per-machine backup files are NOT supported by license.
And backups are encrypted.

Thanks in advance,
Anguel

[PetrM]

Hi Anguel,

Not sure that you really need to use this option with XFS as it already enables reduced storage consumption thanks to fast clone technology. Moreover, VM data will not be compressed if encryption is enabled for a job and the "Decompress backup data blocks before storing" check box is selected, thus more data must be transferred over the network channel from the Source Data Mover to the target one.

Thanks!

[Gostev]

As XFS seems to feature deduplication

XFS does not actually offer deduplication so don't worry about that check box. You're probably confusing it with ReFS, which does offer one (but we don't recommend enabling it).
Both XFS and ReFS offer block cloning and so all the associated space saving technologies by Veeam. This works regardless of compression or encryption status.

[Anguel]

Thanks, I was actually confused by this:
https://wiki.archlinux.org/title/XFS#Deduplication

[Gostev]

This is talking about reflink, which is block cloning.

The author is using wrong terminology:
Deduplication deals with duplication after it has already happened.
Block cloning prevents duplication from happening in the first place.

[DonZoomik]

In case of XFS, it's actually the same thing. While ReFS block clone and deduplication use effectively mutually exclusive technologies, XFS block clone and dedup are the same thing, reflinks. So in theory you could further dedup XFS (after Veeam block clone), I'm just not sure if it's really worth it or Veeam support would approve (though it shouldn't disturb Veeam in any way).