[clue-tech] Linux LVM corruption?

[Jim Ockers]

Hi CLUEbies,

We're working on re-architecting an industrial computer system that used
to use a normal partition table and ext3 filesystem.

We are proposing to use LVM and virtual volumes so that in the event we
might want to resize a partition later on, we could do it in software.
This industrial computer is subject to very bad environmental conditions
including bad power.  They "phsyical disk" is an industrial compactflash
(CF) module which is directly connected to the IDE controller.

Basically the argument for LVM is that the bits on the disk have to be in
some sort of pre-determined arrangement in order to be usable.  Whether
we organize the bits into "a partition table" and "filesystems" shouldn't make
too much difference compared to organizing them into "LVM metadata" and
"volume groups" and so on.  Of course we would continue to use ext3 file-
system inside the logical volumes.

We haven't noticed a huge pile of problems using our existing disk partitions
and filesystems going corrupt under these conditions.  However we are 
wondering if anyone out there has had much experience with LVM and if you've
ever had an LVM go corrupt.

Please feel free to comment on any of the following questions:

1. Is an LVM any more or less likely to become corrupt than just a normal
partition table?  My inkling is no.

2. If we issue a filesystem resize sequence of events/commands and the
power is lost at a bad moment, how likely is it that the failure would be
unrecoverable?  I have no idea.

3. How often does the LVM metadata turn into garbage?  My inkling is not
very often but I'd like to hear some stories.

Thanks a lot for thinking about this,
Jim

-- 
Jim Ockers, P.Eng. (ockers at ockers.net)
Contact info: please see http://www.ockers.net/