On Sun, Sep 16, 2018 at 5:14 AM, Rory Campbell-Lange <r...@campbell-lange.net> wrote: > Hi > > We have a backup machine that has been happily running its backup > partitions on btrfs (on top of a luks encrypted disks) for a few years. > > Our backup partition is on /bkp which is a top level subvolume. > Data, RAID1: total=2.52TiB, used=1.36TiB > There are no other subvolumes.
and > /dev/mapper/cdisk2 on /bkp type btrfs > (rw,noatime,compress=lzo,space_cache,subvolid=5,subvol=/) I like Hans' 2nd email advice to snapshot the top level subvolume. I would start out with: btrfs sub snap -r /bkp /bkp/toplevel.ro And that way I shouldn't be able to F this up irreversibly if I make a mistake. :-D And then do another snapshot that's rw: btrfs sub snap /bkp /bkp/bkpsnap cd /bkp/bkpsnap Now remove everything except "backupdir". Then move everything out of backupdir including any hidden files. Then rmdir backupdir. Then you can rename the snapshot/subvolume cd .. mv bkpsnap backup That's less metadata writes than creating a new subvolume, and reflink copying the backup dir, e.g. cp -a --reflink /bkp/backupdir /bkp/backupsubvol That could take a long time because all the metadata is fully read, modified (new inodes) and written out. But either way it should work. -- Chris Murphy
