[Xen-users] Installing Xen on Debian Sarge

[Miguel Enrique Cobá Martínez <miguel_coba@xxxxxxxxxxx>]

I have sent this mail to debian-user@xxxxxxxxxxxxxxxx, but I have gotten 
any answers. Maybe I should have sent it here first.
I have the following machine:

System:
 - Debian Sarge, stock debian kernel, fully updated pkgs.
 - uname -a:
        Linux debian 2.6.8-2-386 #1 Thu May 19 17:40:50 JST 2005 i686 GNU/Linux
 - Nvidia drivers built with module-assistant:          
        nvidia-kernel-2.6.8-2-386_1.0.7174-3+2.6.8-16_i386.deb

 - root filesystem on LVM
 - /etc/fstab (extract)

/dev/mapper/debianvg-rootlv /     reiserfs defaults 0 1
/dev/hda3                   /boot ext3     defaults 0 2
/dev/mapper/debianvg-homelv /home reiserfs defaults 0 2
/dev/hda5                   none  swap     sw       0 0

- Pentium IV 2.0GHz, 384 MB RAM
- 2 IDE's:
        hda: for current debian sarge, dual booted with W2K
        hdb: data plus free space for lvm for the xen domU's
- 1 ethernic 10/100 Mb  with tulip driver


I have read a lot of sites regarding the various ways of setting up
debian sarge to run Xen.

- http://mark.foster.cc/wiki/index.php/Xen_Tips
- http://mark.foster.cc/wiki/index.php/Debian_Sarge_on_Xen
- http://jclement.ca/xen/host_setup.html
- http://wiki.xensource.com/xenwiki/DebianDomU
- http://dhassler.com/snipsnap/space/UnixResources/InstallingXen
- http://cosi.clarkson.edu/knowledge/workshops/sp05/installingxen/
xen-tutorial.html
- http://wiki.blitzed.org/User:grifferz/Xen
- http://www.option-c.com/xwiki/Xen_Debian_Quick_Start
- http://julien.danjou.info/xen.html
Too much information to swallow.

A couple of remarks,

1. Almost all of these docs are about installing Xen. Just one site has
scenarios where you would like to use Xen as the optimal solution.
2. They are all about installing on plain devices, not lvm volumes.

I will be testing a distributed system I built for work. For this I need
a central node and 10 remote nodes. I thought that Xen will be the
perfect solution. Just create 11 DomUs with minimal debian in each one,
run the test of the system and collect statistics.

I have put a lot of time in my current desktop, so I would like to
continue using my desktop, but running as Dom0. I would like to use the
second hard drive to install the virtual machines.

After a lot of problems and 3 days of search and testing I finally
booted my machine as Dom0. These are the steps I followed:

1. I used the unstable pkgs for xen
2. I downloaded the src from:
http://www.cl.cam.ac.uk/Research/SRG/netos/xen/downloads/xen-2.0.7-src.tgz
and compiled using my current kernel config in /boot.
3. I installed the new XenLinux kernel in /boot and configured menu.lst
according.
3. I had to build a initrd image so that the boot process could mount
the root partition on lvm. I use the script from
/usr/share/doc/lvm2/examples/lvm2create_initrd.gz
to build the initrd, as mkinitrd has a bug with lvm root partitions.
4. I updated grub to use the initrd and all worked ok.

After that, I had my system running Xen but without graphical setup.
This is  not a problem, as I probably could configured correctly with
patience.
I am now ready for creating domains for the real work and I can say that
I have managed to install Xen successfully.
In spite of that, I have the feeling that the solution isn't optimal or
the best.

So, the questions:

- I'm doing this the proper way?

- Is this the intended way of installing Xen?
I mean, should I use my configured and personalised original machine
(postgresql, apache, firefox, thunderbird, /home, etc) on top of Xen as
Dom0 and from time to time to create DomUs for specific task? Or should
I use a minimal debian for Dom0, just for hosting the DomUs and use one
of the DomU as workstation, with all my configuration and selection of
packages inside and the other DomUs for working as needed?

- If I use Dom0 for my workstation, I think I will have full control of
all the others DomUs, and I could use them as I wanted. I could access
it with xm console without problems. But if I use one DomU for my
workstation how could I access the other DomUs? With ssh or vnc only?
What happend if I wanted to access the DomO from DomU? I think that I
couldn't do that.

- What will pass with the updates of my kernel in Dom0?  Will I need to
redo all the steps for configuring my new xen-enabled kernel, creating
an initrd image, compiling nvidia drivers and, when my Dom0 was updated,
then update all of my DomUs?

A don't want to create a flame war, but I would like to hear the
scenarios you used and the decisions you made when configuring Xen.
Also, I would like to read your toughts about your use of Xen.

Thank you all for the answers, in advance

Miguel Cobá






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