On Fri, 29 Jan 2010 05:17:10 +0100 (CET)
Mikael Abrahamsson [off-list ref] wrote:

On Thu, 28 Jan 2010, Mikael Abrahamsson wrote:

quoted

I have a ubuntu 9.04 system with the default mdadm and kernel (2.6.28).

I thought this might be a driver issue, so I tried upgrading to 9.10 which 
contains kernel 2.6.31 and mdadm 2.6.7.1. It seems the sw was unrelated, 
because now during the night three drives were kicked, so I now have 6 
drives, 3 "State: clean", 3 are "State: active", 1 of the "active" ones 
has a different event count. The array shows similar problems, sometimes 
it will assemble will all 6 drives being (S)pares, sometimes it'll 
assemble with 5 drives and shows as "inactive" in /proc/mdstat.

1/ I think you are hitting and mdadm bug in "--assemble --force" that was
   fixed in 2.6.8. (git commit 4e9a6ff778cdc58dc).

2/ Don't poke thing in /sys unless you really know what you are doing (though
   I don't think this has causes you any problems).
3/ You really need to fix your problem with SATA timeouts or the array is
   never going to work.
4/ please (please please) don't use pastebin.  Just include the output inline
   in the mail message.  It is much easer to get at then.

NeilBrown

After finding 
<http://www.linuxquestions.org/questions/linux-general-1/raid5-with-mdadm-does-not-ron-or-rebuild-505361/> 
I tried this:

root@ub:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : inactive sdd[0] sdf[7] sdc[4] sdb[2] sdg[6]
       9767572240 blocks super 1.2

unused devices: <none>
root@ub:~# cat /sys/block/md0/md/array_state
inactive
root@ub:~# echo "clean" > /sys/block/md0/md/array_state
-bash: echo: write error: Invalid argument
root@ub:~# cat /sys/block/md0/md/array_state
inactive

Still no go. Anyone who can help me what might be going wrong here, I 
mean, that a drive is stuck in "active" can't be a very weird event 
state?