Trouble in LVM land

[Lennart Sorensen]

On Wed, Feb 07, 2007 at 12:19:23PM -0500, Merv Curley wrote:
> Well my good experience with LVM didn't last long.
> 
> A couple of days ago, my Mythtv backend computer would not boot up.  All the 
> startup stuff seems to go along well then it halts with
>   can't find videolv01
> A helpful message is to use another superblock and e2fsck. Tried that but it 
> doesn't let e2fsck access hda3.
> 
> Situation on the drive  [ setup with the MythDora distro ]
> hda1       150 MB    ext3     /boot
> hda2             7 GB    LVM      rootvg
>                                 rootlv01   /
>                                 rootlv02    swap
> hda3        236 GB     LVM     videovg
>                                  videolv01    /video 
> 
> To complicate things   I extended   videolv01  with   hdb.  I doubt that 
> anything has been written to hdb yet since I haven't done much TV watching. I 
> don't know if the trouble might be caused by hdb or not. Can I just 
> disconnect  hdb?

If hdb isn't working, perhaps it can't start the videovg.  What does
vgdisplay say?  All parts of a volume group must be present to access
any of it.  VGs spanning multiple devices run the same risks as raid0 in
that you loose one device, you loose it all.  Generally it is recomended
that all physical volumes in LVM run raid1 or higher.  That is how I run
all my LVMs (raid1 devices as the PVs for everything).

> I do have a couple of movies and TV shows on the logical volume videolv01, but 
> if I have to lose them, it isn't the end of the world.  However without being 
> able to boot up, I don't know how to use any of the LVM tools like lvreduce 
> or lvremove that I see listed.

Well being able to boot and fix things is exactly why I will never put /
on LVM.

> Help from my LVM tutors? I hope that I have supplied enough info.

Well my advice was not to put root on LVM, since well it's hard to debug
when you can't boot unfortunately.  Can you boot a previous kernel?
maybe a kernel upgrade broke booting.

--
Len Sorensen
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