BTRFS, backup snapshot to non-BTRFS device possible?

Software & Operating Systems Linux
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1

i have a server, and i have a nas.
some partitions on my server (including the system’s root) use BTRFS, i chose BTRFS after reading about its ability to “snapshot” a filesystem and make a backup without needing to reboot the machine.

however, i wish to backup to my XFS mass storage partition on my NAS. BTRFS send and BTRFS receive seem to only work when sending to another BTRFS partition.
I’ve tried just having BTRFS send output to a file on my XFS, but it always gives an error.

is there any simple way one can backup a BTRFS snapshot to a SINGLE FILE on an XFS partition? changing filesystem formats is not an option I’m willing to entertain at this time.

2

like tar? … or like squashfs or like mkfs.ext4 -d? or like something using rsync? (or mkfs.btrfs -d or -r

3

I’m not sure if tar or rsync are viable solutions as im looking to preserve the btrfs metadata so that i only need to use “btrfs receive” to revert to a backup.

4

I was afraid you were going to say that - I’m not entirely sure ooth what metadata can be preserved with those image making or tarring approaches.

tar / rsync can preserve some additional attributes, but I think most folks are happy even without any extended attributes or facls.

you could redirect btrfs send into a file, but I don’t know if there’s a way to make that mountable, and restore bits and pieces of it as needed (which in my mind makes it a bad backup).

5

i have tried redirecting to a file. it always fails. i believe this to be from BTRFS send not supporting non-BTRFS formats at all.

6

I just tried it, briefly and it worked for me (suckies thing to say ever).

btrfs send /path/to/where/the/subvol/is/mounted > /dev/shm/my_archive … and that was fine. /dev/shm is a tmpfs (not btrfs).