[fedora-virt] Fedora virtualization -- comments and questions

Gene Czarcinski gene at czarc.net
Thu Jun 25 16:11:24 UTC 2009

On Thursday 25 June 2009 10:28:50 Gerry Maddock wrote:
>  From: Gene Czarcinski <gene at czarc.net>
> > I am a newcomer to Fedora (linux) virtualization.  However, I have
> > been a long
> > time user of VMware products running first on Red Hat Linux and then on
> Fedora.
> > When I recently acquired a CPU with hardware virtualization support (AMD
> > Phenom II 940), I decided to "change my problem set" and give Fedora
> > Virtualization a try ... specifically qemu/kvm/etc.
> >
> > I use virtuals for three purposes: 1) To test software which might
> destroy a
> > system or testing which requires a lot of re-booting.  2) For development
> >
> > environment to build rpm packages for various systems, i386/x86_64, etc.
> 3)
> > To run windows.
> >
> > OK, install the virtualization packages and then install a simple Fedora
> 11
> > guest ... naturally it worked fine.
> >
> > Now lets get down to real business since I would be installing/running a
> > number of virtual systems.  The first thing I found was that
> > configuration files,
> > disk images, etc. were scattered but mostly under /etc/libvirt and
> > /var/lib/libvirt.  I looked for a runtime parameter which specified where
> >
> > things were to be stored but did not find anything.  Furthermore, all of
> this
> > stuff was in the root ("/") partition and, when I upgraded to the
> > next release,
> > a pain to bring across.
> >
> > I have three suggestions (I will put these in bugzilla as soon as
> > someone says
> > what package they should be filed against):
> >
> > 1. Put all files (disk images, configuration, etc.) under a single
> directory
> > (easier to manage).
> >
> > 2. Provide a virtualization configuration parameter for setting the top
> > directory to be used to store virtualization files (make it easier to get
> >
> > things out of root).
> >
> > 3. Do not require DVD/CD ISO images to be in the image directory and do
> not
> > screw with SELinux settings on ISO files.
> >
> > For those unfamiliar with it, this is more or less how VMware stuff
> > sets things
> > up.
> >
> > So much for wishful thinking, how do I make things easier (and get the
> files
> > out of root)?
> >
> > OK, what I have come up with is to create a separate partition for all of
> the
> > files and then "bind mount" it to /var/lib/libvirt and /etc/libvirt.
> >
> > Does this make sense?  Is this going to work? Any other suggestions?
> I have been using qemu-kvm pretty much since it was 1st released. All of my
> images have always defaulted to /var/lib/libvirt/images/ and have never
> been "scattered" or anywhere else such as /root. As far as I know CD/DVD
> ISO images could be stored where ever you wanted them (mine never default
> to /var/lib/libvirt/). Not sure by what you mean by: "and do not screw with
> SELinux settings on ISO files".

OK, to properly state my "problem", I need to supply some additional info.

1.  All of my Fedora systems are multiboot systems with a small (minimal 
install) Fedora as a "boot selector" and system to define striped LVM logical 
volumes (which anaconda does not support).  Each system has at least two disk 
drives (they are pretty cheap these days).  There are multiple swap and /boot 
partitions defined.  The remainder of the disk space is put into a single LVM 
volume group.

2.  Basic rule: "do not screw with a working system!" ... Only do fresh 
installs.  NEVER upgrade.  This was a hard lesson to learn but it keeps me out 
of trouble,.

3. Each system has four /boot partitions and four "/" logical volumes (named 
root1-4) ... think of these as old, current, next, and testing.  /home and 
other data are put into separate logical volumes.  One of these separate 
logical volumes has been used for VMware Virtuals.  I keep what goes into a 
"/" (commonly referred to as "root" in Unix/Linux) to just software, etc. for 
a specific version of a system (e.g., Fedora 10, Fedora 11, Fedora 12, etc).  I 
expect all other stuff to be in separate partitions or LVM logical volumes 
which I can mount on my new system.

4.  After installing a "new" system such as when Fedora 12 is released, I want 
to do a minimum of work copying over stuff from the old system to the new 

5.  With the current "libvirt" setup I have disk images under 
/var/lib/libvert/images and the guest's configuration under /etc/libvirt/qemu.  
Furthermore, I now have an application which can chew up a lot of disk space 
and all of it coming out of the "/" logical volume.  I currently size my "/" 
logical volumes to handle a lot of software plus a good amount of temporary 
storage ... BUT I do not have 150GB "/" partitions/logical-volumes!

5.  My current VMware virtuals take about 100GB of storage and I expect Fedora 
Virtualization to need similar resources.  It does not make any sense to me to 
duplicate the storage for each version of the operating system I have 

Now, will mount-bind work?  Does anyone have a better suggestion?  Leaving it 
as-is is not an option.

As far as SELinux goes, I read (somewhere in documentation) that a) iso images 
had to be under /var/lib/libvirt/images and that b) the SELinux context values 
would be set to "virt_image_t".  This may not be the way the software actual 
works but this is what is described in some related documentation.


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