[mythtv-users] Large Drive setup for myth

Ryan Steffes rbsteffes at gmail.com
Mon Sep 11 18:57:05 UTC 2006

On 9/11/06, jack snodgrass <mrlinuxgroups at gmail.com> wrote:
> Maybe my concerns for LVM are unfounded. I am sure that LVM is
> 'stable' but I'm more concerned with hardware failures.
> Say that you have a 1.5TB LVM partition made up of
> 4-5 drives. What happens to the 1.5TB of data if you
> loose one of the drives? Do you loose just the data
> on the drive... or do you screw up the whole LVM
> partition? How easy is it to get the 1.5TB - less the
> failed drive - back up and available?  I'd hate to loose
> it all if one of the drives cratered.
> I got burned a couple of times with software raid
> and now I'm a bit concerned with 'virtual' drives.
> My software raid mirrored ( perfectly ) my corrupted
> file system. Instead of one bad / corrupted file system,
> I had several raid drive copies of it. ;( They mirror
> part did work....
> jack
> On 9/11/06, list at onnow.net <list at onnow.net> wrote:
> > My only comment on this ( no expertise on how to make Myth play with
> > the partitions ) is that LVM is very stable and reliable.  There
> > should be no fear in using it.  I ahve run 1TB plus LVM with no issues.
> >
> > The points you address are quite interesting and becoming more and
> > more common on this list.  You are at 1.5TB.  I just jumped to 1TB and
> > many users are finding the need to add mass storage that is
> > affordable.  Let us know how you do as I am sure this will become more
> > and more crucial over the months.
> >
> > Mark

The answer is a resounding, "it depends". If you manage to corrupt your
filesystem to the point where it can't find the data on the good drive, you
could lose everything.  This'd be especially true if you stripe the LVM
partitions.  You'd get better performance at the increased risk of failure.

Speaking from personal experience, I, just last week, had to spend my
holiday weekend (and birthday) recovering from a failed drive.  More damage
was done from a mistyped command line than was done by the bad blocks on the
drive itself.  Recovery was very slow and painful, but had I caught the
drive failing earlier, it wouldn't have been nearly so slow.   I just
plunked a new drive in, moved the blocks off the old drive to the new one,
and pulled the old drive out.  I lost a few DVDs with bad blocks in the
middle of them that I will now have to rerip, and a whole bunch of my shows
that I manage to kill myself somehow by mv'ing them into oblivion.

Salvaging an LVM partition is a lot like salvaging a raid, but without the
back ups.  If you detect the problem early enough, you just need a new drive
with enough space to put your old drive on it, and move the partitions over,
then repair any file system problem bad blocks created.

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