[NCLUG] Need help with ether md raid or possibly ext4 corrupted group descriptors

[Mike Jensen]

Hello everyone, I am normally pretty quiet on the board, so I am sorry I
am making a post now that I need help.  But I really need help.  I posted
this question on the fedoraForum, but have not had much help.  I was
hoping this might be a better resource.  I appreciate any help or
direction anyone can point me in, I am not sure what the problem is
exactly and I am too afraid to do anything more at this point in fear of
losing the data on the disk (which I know could happen anyway).

Some background:
I am running 64bit fedora 10, it was running a bit slow (swapping a lot
for unknown reasons)...so I just was going to reboot, it was a proper
reboot (no button presses needed).  When the computer turned back on I got
the message:
EXT4-fs: Block bitmap for group 1920 not in group
EXT4-fs: group descriptor corrupted!
mount: error mounting /dev/root on /sysroot as ext4

Before that it does say that /dev/md0 is started with all three drives, so
I just figured all I needed to do was fsck the array.  But when I boot to
the fedora rescue CD it is not able to build the array automatically.  And
I am not sure if I am assembling the array correctly.  I used the command:
mdadm --build /dev/md0 --level=0 --raid-devices=3 /dev/sda2 /dev/sdb1
/dev/sdc1

But after that when I try to mount /dev/md0 I get:
"unknown filesystem type 'mdraid'"

I went ahead and did a badblock scan on all three drives and it came up
clean.  So the questions are, am I building the array correctly?  If so
why wont the array mount after it is rebuilt?  But even after that, I
still get back to the issues with the ext4 corrupted group descriptors. 
So I am in the end just needing to know what should I do to try and get
past that?  Let me know what information you need from me to help.  Here
is the details of the array after I ran the above mdadm --build command
(hopefully showing that the array was built correctly, I don't see
anything that looks unusual to me).

mdadm --details /dev/md0
        Version :
  Creation Time : Fri Jan 30 04:44:04 2009
     Raid Level : raid0
     Array Size : 349477888 (333.29 GiB 357.87 GB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 0

    Update Time : Fri Jan 30 04:44:04 2009
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

     Chunk Size : 64K

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1



mdadm --examine /dev/sda2
          Magic : a92b4efc
        Version : 0.90.00
           UUID : cd4defc3:a967a311:35c4defb:6a8665f7
  Creation Time : Wed Nov 26 04:01:59 2008
     Raid Level : raid0
  Used Dev Size : 0
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 0

    Update Time : Wed Nov 26 04:01:59 2008
          State : active
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 5289bc0e - correct
         Events : 1

     Chunk Size : 256K

      Number   Major   Minor   RaidDevice State
this     0       8        2        0      active sync   /dev/sda2

   0     0       8        2        0      active sync   /dev/sda2
   1     1       8       17        1      active sync   /dev/sdb1
   2     2       8       33        2      active sync   /dev/sdc1


mdadm --examine /dev/sdb1
          Magic : a92b4efc
        Version : 0.90.00
           UUID : cd4defc3:a967a311:35c4defb:6a8665f7
  Creation Time : Wed Nov 26 04:01:59 2008
     Raid Level : raid0
  Used Dev Size : 0
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 0

    Update Time : Wed Nov 26 04:01:59 2008
          State : active
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 5289bc1f - correct
         Events : 1

     Chunk Size : 256K

      Number   Major   Minor   RaidDevice State
this     1       8       17        1      active sync   /dev/sdb1

   0     0       8        2        0      active sync   /dev/sda2
   1     1       8       17        1      active sync   /dev/sdb1
   2     2       8       33        2      active sync   /dev/sdc1


mdadm --examine /dev/sdc1
          Magic : a92b4efc
        Version : 0.90.00
           UUID : cd4defc3:a967a311:35c4defb:6a8665f7
  Creation Time : Wed Nov 26 04:01:59 2008
     Raid Level : raid0
  Used Dev Size : 0
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 0

    Update Time : Wed Nov 26 04:01:59 2008
          State : active
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 5289bc31 - correct
         Events : 1

     Chunk Size : 256K

      Number   Major   Minor   RaidDevice State
this     2       8       33        2      active sync   /dev/sdc1

   0     0       8        2        0      active sync   /dev/sda2
   1     1       8       17        1      active sync   /dev/sdb1
   2     2       8       33        2      active sync   /dev/sdc1


Thank you so much for reading through this.  I really appreciate your guys
help.
cheers,
Mike Jensen
jent at afkfoo.com