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Old 04-08-2007, 03:42 PM   #1
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Registered: Feb 2006
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mdadm: no device found for /dev/md0


I'm new/old at linux. The good thing about Linux is, once it's setup there is not much the user have to do to maintain it. The problem with it is once it's time to redo the system you've forgotten what you originally did. As in my case, I'm trying to migrate all my machines into one unit.


I have an issue with my system. I'm running Debian 3.1.5 kernel and using mdadm for my raid setup. I have various drives setup



The most important are the /dev/sd[abcd] drives. I'm trying to setup RAID5 on these drives. I have read and followed various instructions on this and other forums and have already configured/rebuild multiple times only to end up with the same result.

The problem is mdadm doesn't appear to be reading /etc/mdadm/mdadm.conf on boot, and because it doesn't get read on boot I always get this message "mdadm: no devices found for /dev/md0". There are also a bunch of other messages that followed, but suffice to say if mdadm can't find any devices belonging to /dev/md0 array it will error out and will not create the array.

The reason I believe mdadm is not reading mdadm.conf is because I can logon and execute the command to assemble the array:
#mdadm -A /dev/md0
mdadm: /dev/md0 has been started with 4 drives.

I also test /etc/fstab by:
#mount -a

#df -h
shows the mounted file system
/dev/md0 101G 33M 96G 1% /raid5

This is a pain especially if I can't rely on the system to complete it's boot-up without pausing at "mdadm: no devices found for /dev/md0" , give root password for maintenance or CONTROL-D to continue.

Here's my /etc/mdadm/mdadm.conf
DEVICE partitions
DEVICE /dev/sda /dev/sdb /dev/sdc /dev/sdd

ARRAY /dev/md0 level=raid5 num-devices=4 UUID=23ff6bb9:eb8d753f:2682b942:7ae393e7

It doesn't matter if I remove the first line "DEVICE partitions" it still pauses

Here's my /etc/fstab

# /etc/fstab: static file system information.
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc defaults 0 0
/dev/hda3 / ext3 defaults,errors=remount-ro 0 1
/dev/hda1 /boot ext3 defaults 0 2
/dev/hdc /done_downloading ext3 defaults 0 2
/dev/hdb1 /downloading ext3 defaults 0 2
/dev/md0 /raid5 ext3 defaults 0 2
/dev/hda2 none swap sw 0 0
/dev/hdd /media/cdrom0 iso9660 ro,user,noauto 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

I've also checked /etc/rd2.d to make sure the link to mdadm is proper...

I've also checked /etc/init.d mdadm and mdadm-raid file, from what I can tell they look proper...

Is there anything else I'm missing? If some linux/mdadm guru or someone experience them me (and I know there are plenty out there) who can give me some info on this problem, I will be extremely greatful.

I know it's a long read but please understand my delimma.
Old 04-09-2007, 09:21 PM   #2
LQ Newbie
Registered: Feb 2006
Posts: 11

Original Poster
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double pose

sorry for multiple post, it seems to error out when I click post. Disregard this post.


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