On Thu, Oct 23, 2014 at 10:35 PM, Zygo Blaxell <ce3g8jdj@xxxxxxxxxxxxxxxxxxxxx> wrote: > > - single profile: we can tolerate zero missing disks, > so we don't allow rw mounts even if degraded. > That seems like the wrong logic here. By all means mount read-only by default for safety, but there should be a way to force a read-write mount on any filesystem, precisely because the RAID modes can be mixed and even if you lose two devices on a RAID1 system not ALL the data is lost if you have more than two drives. By all means return an error when reading a file that is completely missing. By all means have an extra fsck mode that goes ahead and deletes all the missing files (assuming it has metadata) or perhaps moves them all to a new "lost+notfound" subvolume or something. Indeed, if the lost device just happens to not actually contain any data you might be lucky and not lose any data at all when losing a single device in a filesystem that entirely uses the single profile. That would be a bit of an edge case though, but one that is automatically handled if you give the admin the ability to force read-write/etc. -- Rich -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
