[PROBLEM] Suddenly read-only :0

[mk01]

@dbman

be careful with HFS+ outside MAC and forcing RW. such setup is expected to hit troubles sooner or later making the HFS+ doing bad.

HFS(without journal) is ok.

and for XBian / BTRFS / suddenly R/O:
- be sure you are on 3.12.x kernel already (not 3.10.x ! )
- with 3.12.x and hitting RO remount - 99.999% hw issue (RPI itself), too much OC, or too less AC, or bad cabling or bad USBHUB (if on USB drive)

BTRFS is doing checksums of metadata written while checking that during read. RO remount means that just read metadata does not match their CRC at the time of write. making drive RO is actually a GOOD thing as continuing would mean only further and further corruption - spreading like virus.

depending on how severe the dmesg reported error is, "btrfs scrub " can recalculate the "wrong" CRC although keep in mind that either Metadata or the checksum is wrong already meaning we have to consider some file/dir properties being not correct.

but again - 3.10.x kernel could cause this corruption (under some very specific conditions), for 3.12.x no bug like that is known. so if this happens, consider the "HW staff". the "problem" could be even in 10MHz OC difference. And if someone would like to think at this point that why other FS is running OK with the same setup - the answer is it is not. but other filesystems are not checksumming what means "silent corruption" possibly realised much more later - with no way rescuing possible.

(if BTRFS fails totally with no possibility to mount it anymore, there is "btrfs restore" command allowing at least copy content out and reformat).