[mythtv] Problems with using LVM for large storage

[Eric Thelin]

You got lucky.  According to all info I found and my own attempts to
recover if a drive fails completely all LVM tools will give up because
the volume can't be accessed and therefore can't be operated on.  If
you were able to get LVM to remove the drive that is dead you would
then have the problem of XFS not being able to shrink only grow.  So
you cannot remove the dead drive.  From what I read when I installed
LVM I thought this would work but when push came to shove I found out
that LVM can remove a "failing" disk but if your disk just completely
fails your complete array is toast.

Eric

On 5/16/05, Jon Wanderer <jonwanderer at yahoo.com> wrote:
> > One of the main drawbacks I see to an LVM is the inability to upgrade
> > a disk.  If I want to pull a 120GB drive out of the LVM and drop in a
> > 300 GB, it might actually be possible, but a massive in the arse to
> do.
> 
> This is actually a straightforward procedure and can be done with your
> system up and running. I recently had a disk in my LVM began to fail and
> I needed get all of the data off of it. I connected another drive and
> added it to the volume group (pvcreate followed by vgextend). Then I got
> the LVM to move all of the data off of the bad drive (pvmove) and then
> dropped that drive from my volume group (vgreduce). I was able to do all
> of this with the filesystem live, mounted and in use.
> 
> I've had excellent results just using LVM and XFS. I can add drives and
> grow my filesystem while in use (just a pvcreate, vgextend, lvextend and
> xfs_growfs) and remove them as above. If one drive fails, I'll use the
> repair tools and as I don't have the volumes stripped I should only lose
> the files that were on that drive. But that's fine, as I keep everything
> I couldn't stand to lose nice and backed up. I thought about going the
> symbolic link way, but I really wanted one giant pool of space that all
> of the myth components can easily tap into. Plus, I can move my drives
> around, switch from one IDE controller to another, etc, and LVM figures
> it all out without any reconfiguration.
> 
> Cheers,
> Jon
> 
> 
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