Created Montag 15 August 2022
to target with same size
Ensure that source and target partition/disk is unmounted and will not be automounted.
Use partclone.btrfs:
# partclone.btrfs -b -s /dev/<Source> -o /dev/<Target>
Use btrfstune -u to change UUID after copy and before mounting.
Data loss warning: Do NOT try to (auto)mount either original or copy until the UUID has changed
to target with different size
(Src)
The steps to "clone" /source to /target where source and target have different disk size.
Get a list of subvolumes ordered by ogen:
# btrfs subvolume list -qu --sort ogen /<Source>
Sorting is probably enough to guarantee that snapshots or subvolumes which depend on previous ones are handled first. This is important for dealing with Copy-on-Write, because we need to have the base volumes transferred first.
Make all source subvolumes read-only using:
# btrfs property set -ts /<Source>/<Some volume> ro true
ATTENTION Directory or file no-cow attributes get lost.
Now, for each subvolume from the list above, starting at the top, do the following:
If the volume does not have a parent UUID (displayed as -) or the parent UUID does not exist anymore in the list, run:
# btrfs send /<Source>/<Some volume> | btrfs receive /<Target>/<mountpoint>
If the volume does have a parent UUID which still exists, we should have transferred it already because of --sort ogen and we can use that as a base to avoid data duplication. Hence, find the parent UUID's path in the list and run:
# btrfs send -p /<Source>/<Parent>/<Subvolume>/ -c /<Source>/<Parent>/<Subvolume>/ /<Source>/<Some volume>/ | btrfs receive /<Target>/<mountpoint>/
(btrfs would probably guess the -p argument automatically, but I prefer to be explicit).
After running one of the above commands make the target and source read-write again:
# btrfs property set -ts /<Source>/<Some volume> ro false; btrfs property set -ts /<Target>/<Some volume> ro false
-> This step can be skipped if the source has been previously read-only.