I upgraded from Squeeze to Wheezy without problems. But after upgrading to Jessie the system cannot boot anymore (using LILO).

ERROR: Duplicated Volume ID
O 24.1 Loading Linux ....(snip)
BIOS data check successful
Loading, please wait
[   14.948425] end_request: I/O error, dev fd0, sector 0
mdadm: /dev/md3 has been started with 1 drive (out of 2).
[   27.196906] end_request: I/O error, dev fd0, sector 0


modprobe: module unknown not found in modules.dep
fsck from util-linux 2.25.2
mount: mounting /dev/root on /root failed: No such file or directory


And i get to the (initramfs) prompt

When I try to list partitions of one of the RAID disks they don't show up.

(initramfs) ls /dev/sda*

Examining the disk says

(initramfs) mdadm --examine /dev/sda
          Magic : Intel Raid ISM Cfg Sig.

Although the onboard RAID controller is disabled in BIOS. When I access the disks with KNOPPIX (7.0.5) I can access and sync the partitions (sda1, sdc1) without problems. So I guess:

  • The RAID disks have been created some time in the past using the onboard RAID controller
  • Because debian didn't support ICH9 chipset the support for this was disabled in BIOS
  • Jessie seems to look not only at the superblocks of the partitions but also on the superblocks of disks and fails because they are identical?

How should I fix this problem?

  • Enable ICH9 raid in BIOS resync the disks there? Will the system boot?
  • Zero-out the superblocks using mdadm on the disks
  • 1
    Run mdadm --examine on /dev/sd* not just sda. Also show what /proc/mdstat looks in Knoppix where things work. If this is a pure Linux system and you're using FakeRAID it would probably be better to switch to mdadm's native format. – frostschutz Oct 10 '15 at 10:29
  • The same result as mdadm --examine /dev/sda comes for sdc (which is the duplicate. I'll try to switch back to the native format and provide the results here. – Gerd K Oct 11 '15 at 7:53

Finally I found a solution myself. So for anyone who runs into a similar problem:

First of all I made a full disk dump of the non-working raid disks using a live cd.

dd if=/dev/sda bs=10M | gzip -1 > /some/backup/drive/sda.img.gz
dd if=/dev/sdc bs=10M | gzip -1 > /some/backup/drive/sdc.img.gz

I rebooted and removed both disks from the array in the Intel Raid util (after BIOS). Then I booted again with the live cd.

dmraid automatically activated the disk raid. So I had to deactivate it

dmraid -an

Afterwards I checked the status of the partitions

mdadm --examine /dev/sda1
mdadm --examine /dev/sdc1

The sda disk had a wrong superblock. I fixed it and activated the raid.

mdadm --zero-superblock /dev/sda1
mdadm -A --run /dev/md0 /dev/sdc1
mdadm -add /dev/md0 /dev/sda1

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