[mythtv-users] Large Drive setup for myth

Tony Lill ajlill at ajlc.waterloo.on.ca
Mon Sep 11 22:29:25 UTC 2006

I tore down my LVM a while ago, when one of the disks went and took the
whole thing with it. I now have 3 separate local filesystems, and 7
other filesystems on 2 other machines that I use for storage.

The whole thing is managed using symlinks, the automounter, nfs and
some scripts.

I have a script (based on myth_archive from the contrib) that copies
stuff off off the local filesystems onto the nfs mounted partitions
periodically and replaces it with a symlink. It prefentially moves
recordings that don't autoexpire.

/mnt/store is a symlink to one of the local disks. A script checks the
filespace available, and switches the symlink to one of the other
local filesystems when it gets too low. I've had no problem doing this
on the fly. The script also transfers the symlinks to the new

0.20 might have support for multiple recording directories,
so this bit can be retired. I wouldn't use it for remote
directories, though, since you're just increase the chance of getting
nailed by hardware problems.

The only "problem" I've had with this is that when you finish watching
a recording, for some reason the backend has the need to check on a
number of files, which causes a bunch of disks to spin-up and
automount, and that can take a while, and also ruins the point of
spinning down.
Tony Lill,                         Tony.Lill at AJLC.Waterloo.ON.CA
President, A. J. Lill Consultants        fax/data (519) 650 3571
539 Grand Valley Dr., Cambridge, Ont. N3H 2S2     (519) 241 2461
--------------- http://www.ajlc.waterloo.on.ca/ ----------------
"Welcome to All Things UNIX, where if it's not UNIX, it's CRAP!"

"jack snodgrass" <mrlinuxgroups at gmail.com> writes:

> That's why I think I'm leaning towards
> /opt/store1
> /opt/store2
> /opt/store3
> and figureing out how I want to move data to the
> different partitons so that mythtv still knows about them.
> especially with autofs unmounting the partiions as needed
> and letting them spin down..... I think that the multiple,
> smaller partitions will work better. If you loose one... you
> loose just what was there... and not the whole TB
> partition.
> I'm definitly going to move away from lvm.
> Does mythtv have the ability to use something like
> /mtn/store1
> /mnt/store2
> /mnt/store3
> or maybe
> /mnt/store/subdir1
> /mnt/store/subdir2
> etc?
> jack
> On 9/11/06, Ryan Steffes <rbsteffes at gmail.com> wrote:
>> 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.
>> Ryan
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