Bug#548648: Info received (misdetects md RAID UUID)

[Ian MacDonald]

I would like to clarify a few points made in my earlier comments; In
particular that it was blkid that had the incorrect UUID output and that
additional steps I performed to retain my raid data in addition to
correcting the UUID issue that may be relevant to others with this issue
on RAID1. 

In my case blkid was incorrectly showing the wrong UUID for
device /dev/sdb1 (displaying the filesystem UUID rather than the
raid_member UUID). This was mistated/reversed somehow in my above
comments even though the output showed blkid being the culprit.

This was causing the system to boot with a raid array missing a device
due to it being in use during the boot process from its
misidentification.  The resulting fstab UUID mount for /boot appeared to
be the wrong device (/dev/sdb1 instead of /dev/md0) also due to the UUID
error.

This complicated matters as I had to actually preserve my current data
on /dev/sdb1 (that received kernel,initramfs and grub updates) before
wiping the partition and adding it back into the /dev/md0 array to
correct the UUID issue. I did this by performing a few additional steps
prior to the above workaround, that might be relavent to somebody else
with this problem. 

1) umounted /boot (where the UUID was currently in use at /dev/sdb1)
2) failed and removed /dev/sda1 in the current /dev/md0 array
3) added /dev/sdb1 to the current /dev/md0 array
4) re-added /dev/sda1 to the current /dev/md0 array (thereby syncing
my /dev/sdb1 data back onto the the /dev/sda1 raid member)

Then continued with the steps listed in my previous comment

1. Fail and remove the raid member with the UUID issue (..
mdadm /dev/md0 -r /dev/sdb1)
2. Overwrite the partition with random data (dd if=/dev/random
of=/dev/sdb1 ..)
3. Re-add the raid member (mdadm /dev/md0 -a /dev/sdb1)



This system does not have reportbut/Internet access, but relavant
squeeze versions are:

ii  libblkid1                           2.17.2-3.1                  block device id library
ii  mdadm                               3.1.2-2.1                   tool to administer Linux MD arrays (software RAID)
ii  grub-pc                             1.98+20100804-4             GRand Unified Bootloader, version 2 (PC/BIOS version)
ii  udev                                160-1                       /dev/ and hotplug management daemon
ii  initramfs-tools                     0.98.1                      tools for generating an initramfs

Additionally, after performing the above procedure the output from grub,
mdadm and blkid is as follows, noting the correct UUID for the
raid_member /dev/sdb1. 

nexus:~# tune2fs -l /dev/md0 | grep UUID
Filesystem UUID:          4075dce0-fb12-4017-bf1d-1b2d86eee0ec

nexus:~# grub-probe --device /dev/md0 --target=fs_uuid
4075dce0-fb12-4017-bf1d-1b2d86eee0ec
nexus:~# mdadm -D /dev/md0 | grep -i uuid
           UUID : aeaeb946:1e6654da:ca9135eb:329f23c1 (local to host nexus)

nexus:~# blkid
/dev/sda1: UUID="aeaeb946-1e66-54da-ca91-35eb329f23c1" TYPE="linux_raid_member" 
/dev/sdb1: UUID="aeaeb946-1e66-54da-ca91-35eb329f23c1" TYPE="linux_raid_member" 
/dev/md0: UUID="4075dce0-fb12-4017-bf1d-1b2d86eee0ec" TYPE="ext2" 
..

On Mon, 2010-09-06 at 13:57 +0000, Debian Bug Tracking System wrote:
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