9.10 mdadm raid 5 won't assemble

[oiad]

I was previously running ubuntu 9.04 with a 5 disk raid 5. I have had no problem with it, but after doing a clean install of mythbuntu 9.10, 3 of the drives will not assemble. fdisk - l still shows all of the drives as 'linux raid autodetect' as they always have.
when I try to assemble the array I get:

$ sudo mdadm -A --scan
mdadm: /dev/md3 assembled from 2 drives - not enough to start the array.

If I examine either of the two disks they look normal:

$ sudo mdadm --examine /dev/sdc1
/dev/sdc1:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : 50186158:8b9af8a0:e1313e7c:10addf20
  Creation Time : Fri Oct 24 11:57:31 2008
     Raid Level : raid5
  Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
     Array Size : 3907039744 (3726.04 GiB 4000.81 GB)
   Raid Devices : 5
  Total Devices : 5
Preferred Minor : 3

    Update Time : Thu Oct 29 22:47:21 2009
          State : clean
 Active Devices : 5
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 44f7bdce - correct
         Events : 665172

         Layout : left-symmetric
     Chunk Size : 64K

      Number   Major   Minor   RaidDevice State
this     4       8       33        4      active sync   /dev/sdc1

   0     0       8       49        0      active sync   /dev/sdd1
   1     1       8       65        1      active sync
   2     2       8        1        2      active sync
   3     3       8       17        3      active sync
   4     4       8       33        4      active sync   /dev/sdc1

On the other 3 drives it states:

$ sudo mdadm --examine /dev/sda1
mdadm: cannot open /dev/sda1: No such file or directory

The only strange thing that i can find is that when I look at the UUID's these drives don't have one

$ blkid
/dev/sda: TYPE="isw_raid_member" 
/dev/sdb: TYPE="isw_raid_member" 
/dev/sdc1: UUID="50186158-8b9a-f8a0-e131-3e7c10addf20" TYPE="linux_raid_member" 
/dev/sdd1: UUID="50186158-8b9a-f8a0-e131-3e7c10addf20" TYPE="linux_raid_member" 
/dev/sde: TYPE="isw_raid_member"

If anyone has any ideas I would be very grateful

~oiad

[Kokopelli]

There are a couple of other threads from today on the subject:

http://ubuntuforums.org/showthread.php?t=1309842
http://ubuntuforums.org/showthread.php?t=1309849

You might try doing a "nodmraid" boot option.

[oiad]

Thanks for the help. I thought it seemed like it was a problem in karmic, and now I am sure. My problem was from the dmraid thinking 3 of my drives were fake raid instead of mdadm raid.

For anyone else who stumbles across this, I solved it like this:

edit the line /etc/default/grub to look like this

GRUB_CMDLINE_LINUX_DEFAULT="nodmraid quiet splash"

After that you need to update grub

sudo update-grub2

And that was it. Thanks Kokopelli!

[agibby5]

This worked for me too... I only have RAID1 and it wouldn't mount automatically. Adding the nodmraid boot param fixed it. Thanks!