Can't create a snapshot of a Btrfs subvolume
serge.hallyn at ubuntu.com
Tue Jul 29 03:07:36 UTC 2014
Quoting Martín Cigorraga (martincigorraga at gmail.com):
> I recently installed an Ubuntu Server with this layout:
> partition 1: / Btrfs
> partition 2: /home Btrfs
> partition 3: swap
> and I'm unable to create any snapshot of / -- a problem I never had before
> when installing with the default Btrfs layout (that is, with both / and
> /home subvolumes on the same partition).
> My current Btrfs layout is this one:
> UUID=blah-blah-blah / btrfs
> 0 1
> UUID=blah-blah-blah /home btrfs
> defaults,space_cache,autodefrag,relatime,compress-force=zlib,subvol=@home 0
> UUID=blah-blah-blah none swap sw
> 0 0
> Now, when I try to create a snapshot I get this:
> ~> sudo btrfs subvolume snapshot -r / /home/SYSTEM/snapshots/root
> Create a readonly snapshot of '/' in '/home/SYSTEM/snapshots/root'
> ERROR: cannot snapshot '/' - Invalid argument
> (Note: /home/SYSTEM/snapshots directory already exists)
> This is strange because the same exact command does work as expected when /
> and /home subvolumes are in the same partition.
I could be off base, but I would expect precisely this result. I would
not expect btrfs subvolume to be able to create a subvolume in a different
filesystem from the origin subvolume. You could probably use 'btrfs
send/receive' for that, but I've not used those.
Can you just keep your rootfs backups under something like /BACKUPS?
(Keeping in mind of course they won't include /home contents)
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