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I have Linux (Crunchbang 8.10) set up with 3x1TB Hard drives set up as software RAID5.

It has recently suddenly stopped working.

cat /proc/mdstat shows the following:

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : inactive sdd[2](S) sdc[1](S) sdb[0](S)
      2930287488 blocks

unused devices: 

mdadm --detail /dev/md0 shows:

mdadm: md device /dev/md0 does not appear to be active.

I Have tried running sudo mdadm -A /dev/md0 but get:

mdadm: /dev/md0 not identified in config file.

My /etc/mdadm/mdadm.conf shows:

# mdadm.conf
# Please refer to mdadm.conf(5) for information about this file.

# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
DEVICE partitions

# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system

# instruct the monitoring daemon where to send mail alerts

# definitions of existing MD arrays

# This file was auto-generated on Thu, 21 May 2009 18:32:49 +0100
# by mkconf $Id$

Has my config been corrupted? Please help.

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up vote 1 down vote accepted

Looks like your drives are all being reported as [S]pares. You should check your logs (dmesg, /var/log/messages) to see if there's any indication why this happened.

Try running the following

sudo mdadm --examine --scan --config=/etc/mdadm/mdadm.conf

And see the output. If it outputs something like this:

ARRAY /dev/md0 level=raid5 metadata=1 num-devices=3 UUID=22f22c3599:613d5231:d407a655:bdeb84 name=backup:1

Then you can append it to the bottom of the mdadm.conf:

sudo mdadm --examine --scan --config=/etc/mdadm/mdadm.conf >> /etc/mdadm/mdadm.conf

Then try starting the array:

sudo mdadm -A /dev/md0

Good luck.

share|improve this answer
Thanks for the fast response. mdadm --examine --scan --config=/etc/mdadm/mdadm.conf Gives me no output. And dmesg, spouts a lot but not an advanced enough user to locate problem areas.. – iali Aug 16 '10 at 1:50
Ah. I had to use sudo. I get the following: ARRAY /dev/md0 level=raid5 num-devices=3 UUID=adc48f8c:fc8a367a:05731609:dddb53d2 No metadata=1 though. I get permission denied when I try to use your append command. Though I am using sudo command – iali Aug 16 '10 at 1:54
Yes, you need to use sudo for all commands. I edit the post to reflect that. Try running the append command again with sudo. If it doesn't work, edit the mdadm.conf file and paste the contents manually. Then run the last command to assemble the array. – vmfarms Aug 16 '10 at 1:59
Update: I have managed to append the line. I now get "no devices found for /dev/md0" when I try mdadm -A /dev/md0 – iali Aug 16 '10 at 2:00
I ran "sudo mdadm --stop /dev/md0" then "sudo mdadm -A /dev/md0" I get the following message: "mdadm: /dev/md0 assembled from 1 drive - not enough to start the array" – iali Aug 16 '10 at 2:07

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