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I have a problem that I can't seem to solve. We have a Ubuntu server setup with RAID-10 and two of the drives dropped out of the array. When I try to re-add them using the following command:

mdadm --manage --re-add /dev/md2 /dev/sdc1

I get the following error message:

mdadm: Cannot open /dev/sdc1: Device or resource busy

When I do a "cat /proc/mdstat" I get the following:

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [r$
md2 : active raid10 sdb1[0] sdd1[3]
    1953519872 blocks 64K chunks 2 near-copies [4/2] [U__U]

md1 : active raid1 sda2[0] sdc2[1]
    468853696 blocks [2/2] [UU]

md0 : active raid1 sda1[0] sdc1[1]
    19530688 blocks [2/2] [UU]

unused devices: <none>

When I run "/sbin/mdadm --detail /dev/md2" I get the following:

/dev/md2:
    Version : 00.90
Creation Time : Mon Sep  5 23:41:13 2011
   Raid Level : raid10
   Array Size : 1953519872 (1863.02 GiB 2000.40 GB)
Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
  Raid Devices : 4
  Total Devices : 2
Preferred Minor : 2
Persistence : Superblock is persistent

Update Time : Thu Oct 25 09:25:08 2012
      State : active, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0

     Layout : near=2, far=1
Chunk Size : 64K

       UUID : c6d87d27:aeefcb2e:d4453e2e:0b7266cb
     Events : 0.6688691

Number   Major   Minor   RaidDevice State
   0       8       17        0      active sync   /dev/sdb1
   1       0        0        1      removed
   2       0        0        2      removed
   3       8       49        3      active sync   /dev/sdd1

Output of df -h is:

Filesystem            Size  Used Avail Use% Mounted on
/dev/md1              441G  2.0G  416G   1% /
none                   32G  236K   32G   1% /dev
tmpfs                  32G     0   32G   0% /dev/shm
none                   32G  112K   32G   1% /var/run
none                   32G     0   32G   0% /var/lock
none                   32G     0   32G   0% /lib/init/rw
tmpfs                  64G  215M   63G   1% /mnt/vmware
none                  441G  2.0G  416G   1% /var/lib/ureadahead/debugfs
/dev/mapper/RAID10VG-RAID10LV
                  1.8T  139G  1.6T   8% /mnt/RAID10

When I do a "fdisk -l" I can see all the drives needed for the RAID-10.

The RAID-10 is part of the /dev/mapper, could that be the reason why the device is coming back as busy? Anyone have any suggestions on what I can try to get the drives back into the array?

Any help would be greatly appreciated.

Thanks!

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closed as too localized by Marco Ceppi Nov 14 '12 at 17:37

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

    
Have you tried to reboot the server, if that is an option (ie, if the downtime from the reboot won't be an issue)? –  dobey Oct 25 '12 at 16:04
    
Yeah, this is happening after the reboot. –  thiesdiggity Oct 25 '12 at 16:18
    
OK, just had to suggest it, as I had a similar issue recently. The only way I could get it fixed was a reboot. –  dobey Oct 25 '12 at 17:32
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1 Answer 1

up vote 0 down vote accepted

Dumb question, sorry. I looks like the two drives that dropped out are in-fact not being mounted for some reason, probably failed.

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