[dm-devel] dm failure while trying to activate damaged LV

[Cheretakis Christos]

Hello!

Here's my story in short. I had an LVM1 setup with
kernel 2.4, with 4 disks making up a VG. On the VG
lived (and still live, I hope) 3 LV with filesystems.
My trouble starts when one of those disks crashed!

I installed kernel 2.6.7, device mapper and LVM2 tools
to recover the filesystems (yes, there was no backup
earlier than 6 months ago).

I managed to completely recover all filesystems that
are on the LVs not containing the bad disk using the
partial activation feature of LVM2, but I'm getting a
dm error for the one on the problematic disk.

Based on previous postings both on this list and on
the lvm list and various info on man-pages, I created
an ioerror "device" exactly the size of the failed
disk, linked to it from /dev/ioerror, but the LV still
fails to activate.

Following debug messages of LVM, what the code does is
about this:
1) it creates a "soft"-device that is a concatenation
of the original disks & partitions, and replaces the
failed disk with mappings to /dev/ioerror
2) there's not a signle mapping to /dev/ioerror, but
lots of them, each one with size 8192
3) tries to reload the mapping and then fails with
"ioctl cmd 9 failed"

I also tried to recreate a mapping file following what
the lvm code did, and replacing the chunk-mappings of
8192 sectors with one single mapping, but it fails
with the same error.

  Thanx in advance for any help,

      C/


	
		
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