Where's the LVM utils? ( Debian - Ubuntu )

[Tim Writer]

John Van Ostrand <john-Da48MpWaEp0CzWx7n4ubxQ at public.gmane.org> writes:

> On Mon, 2007-01-22 at 10:02 -0500, Lennart Sorensen wrote:
> 
> > Actually having / on LVM always seems like a bad idea to me (I never do
> > it).  
> 
> I do it all the time.

Me too.

> And I'd have /boot on LVM if Grub would support it.

I probably wouldn't go that far.

> > Since the LVM config files are in /etc and being able to do any
> > kind of recovery requires access to the LVM tools (/sbin) having at
> > least that much of my system bootable even if LVM breaks (which I have
> > managed to do before when trying to use pvmove on a whole LVM at once
> > rather than individual LVs), being able to boot and have a working
> > system (although minimal) to repair it is rather handy.  If / is on LVM
> > then you have essentially nothing if it breaks.  You can try and get it
> > repaired using something like knoppix or such, but it will be a lot
> > harder since you still need to assemble the LVM in order to get at the
> > config files needed to assemble the LVM.  
> 
> What about vgscan? It pulls the VG config from the VG descriptor area on
> the disk and reassembles volume groups.

Yes, I've restored LVM using a rescue CD (Knoppix or RIP) and vgscan
numerous times. pvscan is also useful. Note that the LVM tools were removed
from Knoppix at one point; I don't know if they're back.

> > Having a small / for /etc,
> > /boot, /bin and /sbin is much much safer.  No need for having /boot and
> > / seperate of course.  I imagine 500M or so would do for that if /usr
> > and /var are on LVM.  Might be best to actually leave /var on / too and
> > just have seperate LVs for subdirs of /var that need space (like
> > databases in /var/lib and some of the stuff in /var/log, and probablt
> > /var/spool and /var/cache).  I am not entirely sure how important /var
> > might be for booting.

/var is not required for booting. I (almost) always make /var a separate
volume.

> It may be safer but less convenient and it sounds messy.  Now instead of
> efficiently using space you've got lots of spare space devoted to
> subdirs of /var.
> 
> As long as you're resigned to needing a rescue disk when you have to
> repair LVMs then you should be okay.

I think it depends on what you're trying to achieve with LVM.

I use LVM on my notebook to allow me to install multiple versions of Linux
which requires a separate root file system for each distro. Doing this
without root on LVM is a pain. In this case, the benefits of being able to
run multiple distros outweighs any possible loss of safety.

I also use LVM for safe distribution upgrades. For example, when upgrading
from Dapper to Edgy, I cloned my Dapper LVs, booted into them, then
upgraded. Had there been any problem with the upgrade, I could have easily
reverted to Dapper. Again, this is difficult to do without root on LVM. In
addition, I would also argue that this makes a potentially disastrous
operation (a major upgrade) much safer. To my mind, facilitating safe
upgrades is a substantial benefit which more than justifies the slight risk
of root on LVM.

-- 
tim writer <tim-s/rLXaiAEBtBDgjK7y7TUQ at public.gmane.org>                                  starnix inc.
647.722.5301                                      toronto, ontario, canada
http://www.starnix.com              professional linux services & products
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists