On Mon, Jun 10, 2019 at 12:42:26PM +0000, Hugo Mills wrote: > Hi, David, > > On Mon, Jun 10, 2019 at 02:29:40PM +0200, David Sterba wrote: > > this patchset brings the RAID1 with 3 and 4 copies as a separate > > feature as outlined in V1 > > (https://lore.kernel.org/linux-btrfs/cover.1531503452.git.dste...@suse.com/). > [...] > > Compatibility > > ~~~~~~~~~~~~~ > > > > The new block group types cost an incompatibility bit, so old kernel > > will refuse to mount filesystem with RAID1C3 feature, ie. any chunk on > > the filesystem with the new type. > > > > To upgrade existing filesystems use the balance filters eg. from RAID6 > > > > $ btrfs balance start -mconvert=raid1c3 /path > [...] > > If I do: > > $ btrfs balance start -mprofiles=raid13c,convert=raid1 \ > -dprofiles=raid13c,convert=raid6 /path > > will that clear the incompatibility bit?
No the bit will stay, even though there are no chunks of the raid1c3 type. Same for raid5/6. Dropping the bit would need an extra pass trough all chunks after balance, which is feasible and I don't see usability surprises. That you ask means that the current behaviour is probably opposite to what users expect. > (I'm not sure if profiles= and convert= work together, but let's > assume that they do for the purposes of this question). Yes they work together.
