[linux-lvm] Overlapping logical volumes

[Tom Parker]

Hi,

I have just experianced a rather nasty bug in lvextend. I grew a logical
volume and it used extents that were already in use for another logical
volume.

I'm using Debian Woody and Linux 2.4.22 (unpatched Linus kernel.org sources)

amislave:/# lvextend --help

Logical Volume Manager 1.0.4
Heinz Mauelshagen, Sistina Software  02/05/2002 (IOP 10)

Luckily I noticed the corrupting filesystems fairly quickly and was able to
mostly recover the situation with minimal losses. Currently I still have the
two overlapping logical volumes and a lot less trust in the LVM than I had
before.

Is there a program that can validate the logical volume configuration and
ensure that no physical extent is allocated to more the one logical volume?

When extending a logical volume, or creating a new one, is anything written to
the newly allocated extents? If this were to happen again, and I discovered
the problem before I made use of the extra space or a new logical volume,
would I have any corruption of the first logical volume to use the extents in
question?

To finish my data recovery, I would like to allocate another large logical
volume, I'm somewhat wary of doing this without a tool to ensure that the
group is valid.

--
Tom Parker - tom at carrott.org
           - http://www.carrott.org