Re: RAID6 ext3 problems

[NeilBrown <neilb@suse.de>]

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On Sun, 12 Feb 2012 12:52:25 -0800 Mark Knecht <markknecht@gmail.com> wrote:

> On Sun, Feb 12, 2012 at 12:27 PM, Jeff W <jeff.welling@gmail.com> wrote:
> >>
> >> So what _actually_ happens when you issue the commands? Please post
> >> back the results of
> >>
> >> cat /proc/mdstat
> >
> > jeff@Shmee:~$ cat /proc/mdstat
> > Personalities : [raid6] [raid5] [raid4]
> > md1 : active raid6 sda[0] sdf1[1] sdg1[5] sde[4] sdd1[3] sdc1[2]
> >      2441437440 blocks level 6, 64k chunk, algorithm 2 [7/6] [UUUUUU_]
> >
> > unused devices: <none>
> >
> >
> >>
> >> and
> >>
> >> mount /dev/mdWHATEVER /mountpoint
> >
> > jeff@Shmee:~$ sudo mount /dev/md1 /mnt
> > [sudo] password for jeff:
> > mount: wrong fs type, bad option, bad superblock on /dev/md1,
> >       missing codepage or helper program, or other error
> >       In some cases useful info is found in syslog - try
> >       dmesg | tail  or so
> >
> >
> > jeff@Shmee:~$ dmesg | tail
> > [48532.584428] [drm] nouveau 0000:01:00.0: Setting dpms mode 0 on vga
> > encoder (output 0)
> > [49369.880015] [drm] nouveau 0000:01:00.0: Setting dpms mode 1 on vga
> > encoder (output 0)
> > [50470.240278] [drm] nouveau 0000:01:00.0: Setting dpms mode 0 on vga
> > encoder (output 0)
> > [50522.284317] usb 2-6: USB disconnect, address 4
> > [52848.285524] [drm] nouveau 0000:01:00.0: Setting dpms mode 1 on vga
> > encoder (output 0)
> > [52940.534516] [drm] nouveau 0000:01:00.0: Setting dpms mode 0 on vga
> > encoder (output 0)
> > [53540.724023] [drm] nouveau 0000:01:00.0: Setting dpms mode 1 on vga
> > encoder (output 0)
> > [54039.813485] [drm] nouveau 0000:01:00.0: Setting dpms mode 0 on vga
> > encoder (output 0)
> > [58210.212241] EXT3-fs error (device md1): ext3_check_descriptors:
> > Block bitmap for group 6016 not in group (block 277891307)!
> > [58210.247230] EXT3-fs: group descriptors corrupted!
> >
> > Is that more helpful?
> > Thanks!
> > Jeff.
> 
> I think it will be to others. It's a bit above my pay grade unfortunately.
> 
> Doing a quick Google of
> 
> RAID ext3_check_descriptors
> 
> turns up others having similar issues to yours (I think) with a few
> posts that look like solutions, or possible solutions.
> 
> IMPORTANT: My first inclination was to suggest an fsck but one post I
> found made it sound like that hurt his RAID so read carefully before
> doing anything that might cause more hard.

fsck is the only thing I can recommend.
Probably use "-n" first so that it only reads and never writes.  Then you can
see how much damage there appears to be before deciding if you want to fix it
(rather than ask for more suggestions).

'sda' must be left over from some other array.. Maybe 'sda1' had the other
device from your current array??

I suspect that when you had the problem that caused you to want to move the
array to a new machine, something corrupted the filesystem a little -
probably not very much.  fsck for ext3 is pretty good at fixing things so
you'll probably get your data back.

NeilBrown

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