[mythtv-users] Moving drives containing LVM2 volumes, change of partition device nodes

[Tom Dexter]

I'm thinking about possibly restructuring my mythbackend and adding a
hard drive so as to avoid my current situation where my OS (and my
mysql database etc) are on a drive used by my video LVM2 volume.

Currently I have two 500 GB drives.  The hda1, hda2, and hda3
partitions are used for /boot, swap and / respectively.  The hda4 and
hdb1 partitions are LVM2 physical volumes, both of which are assigned
to one volume group named 'vg'.  Over that I have to logical volumes,
'home' and 'video' used for /home and /video respectively...the latter
being used for my mythtv recordings.

If I can, I'd like to add a new hard drive that will be used for
everything except the mythtv recordings which will become hda, and
move the existing two drives which will then be strictly for
recordings.  I'm actually not sure if I'd be better off with both of
the video drives on the secondary IDE (hdc and hdd) or with one on the
primary (hdb and hdc for example)...I'm thinking that it'd be best to
put them both on the secondary....suggestions welcome.  I do almost
nothing with the CD drive so that's not a performance factor at all.

I know my way around well enough to do this, but one aspect of the
LVM2 end of it has me confused, and I'm not finding anything that
clears this up: If I do this, obviously the old hda4 and hdb1
partitions will change depending on how I move things around (for
example to hdc4 and hdd1).  What exactly (if anything) to I need to do
with LVM?  I see my existing partition device names (hda4 and hdb1)
referenced in my current /etc/lvm/backups/vg backup file.

Does LVM2 care about those actual device names or does it strictly
depend on it's own unique identifiers physically stored on the drives?
 That is, once the drives are moved will the following:

vgscan
vgchange -a y

...simply find everything, creating the /dev/vg/home and /dev/vg/video nodes?

Also, on a related note:  My backend machine is a dell 4600.  I've
read that people have successfully added a third IDE drive mounted
where the second CD would go.  Is anyone offhand aware of any
compelling reasons not to try that?  I suppose cooling and power could
be an issue.

Thanks in advance.

Tom