On Sat, Jan 23, 2021 at 7:50 AM Jakob Schöttl <jscho...@gmail.com> wrote: > > Hi, > > In short: > When mounting a second subvolume from a pool, I get this error: > "mount: /mnt: wrong fs type, bad option, bad superblock on /dev/sda, > missing code page or helper program, or other." > dmesg | grep BTRFS only shows this error: > info (device sda): disk space caching is enabled > error (device sda): Remounting read-write after error is not allowed
It went read-only before this because it's confused. You need to unmount it before it can be mounted rw. In some cases a reboot is needed. > > What happened: > > In my RAID1 pool with two disk, I successfully replaced one disk with > > btrfs replace start 2 /dev/sdx > > After that, I mounted the pool and did I don't understand this sequence. In order to do a replace, the file system is already mounted. > > btrfs fi show /mnt > > which showed WARNINGs about > "filesystems with multiple block group profiles detected" > (don't remember exactly) > > I thought it is a good idea to do > > btrfs balance start /mnt > > which finished without errors. Balance alone does not convert block groups to a new profile. You have to explicitly select a conversion filter, e.g. btrfs balance start -dconvert=raid1,soft -mconvert=raid1,soft /mnt > Now, I can only mount one (sub)volume of the pool at a time. Others can > only be mounted read-only. See error messages at top of this mail. > > Do you have any idea what happened or how to fix it? > > I already tried rescue zero-log and super-recovery which was successful > but didn't help. I advise anticipating the confusion will get worse, and take the opportunity to refresh the backups. That's the top priority, not fixing the file system. Next let us know the following: kernel version btrfs-progs version Output from commands: btrfs fi us /mnt btrfs check --readonly -- Chris Murphy
