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At boot my mdadm raid5 array fails to start, saying that one of my disks (sdi) has a bad superblock. However, once I log in, I can start the array no problem with mdadm --assemble /dev/md0 /dev/sd[abcdehijk]1.

Everything looks fine in output from cat /proc/mdstat and mdadm --detail /dev/md0. The array mounts fine too, and all files seem to be present and accessible.

How can I make the array assemble and mount at boot?

I'm also about to resize the filesystem (ext3), and thought I'd post here before I potentially borked my array.


asmithee@serv:~# uname -a
Linux serv 3.2.0-4-686-pae #1 SMP Debian 3.2.51-1 i686 GNU/Linux
asmithee@serv:~# cat /etc/debian_version 
asmithee@serv:~# mdadm --version
mdadm - v3.2.5 - 18th May 2012

Ask and I can provide more output.

Edit: some more outputs:

asmithee@serv:~# cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
md0 : active raid6 sdc1[0] sdb1[11] sde1[7] sda1[6] sdk1[10] sdi1[9] sdj1[4] sdd1[2] sdh1[8]
       6837315072 blocks super 1.2 level 6, 512k chunk, algorithm 2 [9/9] [UUUUUUUUU]

unused devices: <none> 

asmithee@serv:~# mdadm --detail /dev/md0 
        Version : 1.2
  Creation Time : Wed Feb  6 00:59:56 2013
     Raid Level : raid6
     Array Size : 6837315072 (6520.57 GiB 7001.41 GB)
  Used Dev Size : 976759296 (931.51 GiB 1000.20 GB)
   Raid Devices : 9
  Total Devices : 9
    Persistence : Superblock is persistent

    Update Time : Sun Jan 19 11:03:50 2014
          State : clean 
 Active Devices : 9
 Working Devices : 9
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : serv:0
           UUID : 1f2e489b:8d47feac:2e08c3c4:0cbd2575
         Events : 56337

    Number   Major   Minor   RaidDevice State
       0       8       33        0      active sync   /dev/sdc1
       8       8      113        1      active sync   /dev/sdh1
       2       8       49        2      active sync   /dev/sdd1
       4       8      145        3      active sync   /dev/sdj1
       9       8      129        4      active sync   /dev/sdi1
      10       8      161        5      active sync   /dev/sdk1
       6       8        1        6      active sync   /dev/sda1
       7       8       65        7      active sync   /dev/sde1
      11       8       17        8      active sync   /dev/sdb1

Is everything alright here? Anyone know why the array complains about a bad superblock on sdi and refuses to mount at boot?

share|improve this question
What exactly are you mounting? If you're mounting /dev/md0 directly, then there's not supposed to be a partition table, stop trying to use fdisk on it (otherwise see ). – DerfK Jan 17 '14 at 5:19
Yes, I am indeed mounting md0 directly. I guess I was thinking that if sdX and sdXN are device and partition, md and mdN would be the same, but now that I type it out I see what you mean. I'll edit my question to just ask about the invalid superblock, thanks. – ACK_stoverflow Jan 17 '14 at 12:18
What does cat /proc/mdstat say now that you have assembled the raid array yourself? – DerfK Jan 17 '14 at 20:20
I can provide complete output tomorrow morning, but to me it indicates no issues (it's clean, has UUUUUUUUU, etc). – ACK_stoverflow Jan 17 '14 at 21:41

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