[ale] Software raid 0 getting strnage errors.

[Jim Lynch]

I first noticed that I had a problem when I received the following email:

A DegradedArray event had been detected on md device /dev/md0.


I did a google on this error and found that it's probably because of an 
unclean mount.  I suspect that happened during a storm when power went 
out. 

a cat of /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] 
[raid4] [multipath]
md0 : active raid1 hda5[1]
      93771264 blocks [2/1] [_U]

unused devices: <none>

Sure enough /dev/hdb5 is missing.  However when I attempt to add it back 
in, I get:

root at chinaberry:~# umount /dev/md0
root at chinaberry:~# mdadm /dev/md0  --add /dev/hdb5
mdadm: Cannot open /dev/hdb5: Device or resource busy

I even tried it running as single user but that didn't help.  Google 
shows a couple of different ways to fix, but others included utilities 
like raidstop that apparently aren't available on Ubuntu.

chinaberry:~$ fuser /dev/hdb5
chinaberry:~$     

  fdisk -l /dev/hdb

Disk /dev/hdb: 120.0 GB, 120034123776 bytes
255 heads, 63 sectors/track, 14593 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1               1         973     7815591   83  Linux
/dev/hdb2             974        1946     7815622+  83  Linux
/dev/hdb3            1947        2919     7815622+  83  Linux
/dev/hdb4            2920       14593    93771405    5  Extended
/dev/hdb5            2920       14593    93771373+  83  Linux
        

Other than wipe the disks and start over, is there anything I can do?

chinaberry:~# mdadm -E /dev/hdb5
/dev/hdb5:
          Magic : a92b4efc
        Version : 00.90.01
           UUID : d01d66b4:16efa6c2:d7493088:59f3fe68
  Creation Time : Fri Feb 23 15:03:40 2007
     Raid Level : raid1
    Device Size : 93771264 (89.43 GiB 96.02 GB)
     Array Size : 93771264 (89.43 GiB 96.02 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0

    Update Time : Sun Sep 16 07:35:53 2007
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 53d8c033 - correct
         Events : 0.4


      Number   Major   Minor   RaidDevice State
this     0       3       69        0      active sync   /dev/hdb5

   0     0       3       69        0      active sync   /dev/hdb5
   1     1       3        5        1      active sync   /dev/hda5

As it flashed by I saw something about /dev/hdb5 being kicked-off, but 
that error isn't in any log, so I don't know the details.