Re: Error mounting multi-device fs after restart

[Diwaker Gupta <diwaker@maginatics.com>]

>> The system was running overnight when I first hit the problem. On
>> subsequent reboots, I've only waited less than half an hour. Usually
>> the mount is instantaneous, so I wasn't sure if waiting would help a=
t
>> all. The error messages did not indicate that the system could recov=
er
>> at that stage. If there's even a slight chance that the fs would
>> eventually mount, I'm happy to let it run for a day or two. Note tha=
t
>> if I mount using the 'degraded' option, the mount succeeds but
>> subsequent attempts to read the data fail.
>
> Huh. =A0How do those attempts fail?

Same way when I try to do a regular mount: the read blocks and I see a
continuous stream of the 'parent transid verify failed' messages in
dmesg.

> Try mounting ro, or degraded,ro, and reading the data off. =A0That
> worked for me recently on a broken btrfs raid10 (and didn't on anothe=
r
> one, so your mileage may vary).

Ok I'll give these a shot. I still don't quite understand what it
means if btrfsck aborts; if it can't find the superblock on any of the
drives, how would btrfs ever be able to mount the fs?

Diwaker
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