Xen users - Feb 2009 - 3 failed approaches to create guest domains

Hello all,

I am a Masters student working on my thesis and have to go use Xen for live
migration purposes. I have a Xen installation on Fedora 8, and been trying
for past 3 months to create guest domains and get them running for further
migration work. I took 3 different approaches, but got stuck with each of
those. I would be very grateful if you could point out as to where I am
going wrong...
*
1. Basic command:
xm create -c vm01-config.sxp vmid=1*

The config file is kept in /etc/xen folder.

ERROR:
VFS: Cannot open root device "hd0" or unknown-block(0,0)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(0,0)

WHAT I PUT IN:
root = ''/dev/hd0'' or ''/dev/hda'' or
''/dev/sda2''

None worked. I am not sure what the option should be.

*
2. Using the command:
virt-install -f /etc/xen/xen1 -r 256*

WHAT IT DOES:
Asks for config parameters and creates virtual machine, but I am not sure
how to proceed with completion process. In the install location, I put in a
OS image at a mirror site:
http://ringtail.its.monash.edu.au/pub/fedora/linux/releases/8/Fedora/i386/os/

ERROR:
Unable to find image at given location

This is the only approach which creates a VM, but the machine is not
completely running (not functional or doesnt consume any memory). Am I
supposed to have the guest image on my machine?


*3. Using "virt-manager" in GUI*

ERROR: Asks for "Connect to host  network" *but "shared physical
devices"
list is empty*. It is supposed to list eth0, peth0 etc. Something to do with
creating a bridge. I tried the approach of NAT, but for that I have to use
approach 1 to create a machine, which gets stuck on "root" error.


Libvirtd is not running. It gave the message:
libvir: Remote error : Connection refused
libvir: warning : Failed to find the network: Is the daemon running ?
libvir: Remote error : Connection refused

xend is running, I checked status.





If anyone could devote a little of their time to help me out, as I am not
comfortable with kernel administration/OS admin, I would be really thankful.

Thanks & Regards,
Siddharth Wagh
-----------------------------------------------------------------------------------------
To ensure perfect aim, shoot first and call whatever you hit the target...
-----------------------------------------------------------------------------------------

On Thu, Feb 12, 2009 at 4:32 AM, Siddharth Wagh
<siddharth.wagh@gmail.com> wrote:
> I am not
> comfortable with kernel administration/OS admin
In that case I suggest you switch to Centos 5.2 (or RHEL 5.3, if you
can afford it), choose virtualization support during installation, and
try again. Manual is available on

http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualization_Guide/index.html

or

http://www.centos.org/docs/5/html/5.2/Virtualization/

Regards,

Fajar

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Siddharth Wagh wrote:
> Hello all,
> 
> I am a Masters student working on my thesis and have to go use Xen for 
> live migration purposes. I have a Xen installation on Fedora 8, and been 
> trying for past 3 months to create guest domains and get them running 
> for further migration work. I took 3 different approaches, but got stuck 
> with each of those. I would be very grateful if you could point out as 
> to where I am going wrong...
> *
> 1. Basic command:
> xm create -c vm01-config.sxp vmid=1*
> 
> The config file is kept in /etc/xen folder.
> 
> ERROR:
> VFS: Cannot open root device "hd0" or unknown-block(0,0)
> Please append a correct "root=" boot option
> Kernel panic - not syncing: VFS: Unable to mount root fs on 
> unknown-block(0,0)
> 
> WHAT I PUT IN:
> root = ''/dev/hd0'' or ''/dev/hda'' or
''/dev/sda2''
> 
> None worked. I am not sure what the option should be.
> 
> *
> 2. Using the command:
> virt-install -f /etc/xen/xen1 -r 256*
> 
> WHAT IT DOES:
> Asks for config parameters and creates virtual machine, but I am not 
> sure how to proceed with completion process. In the install location, I 
> put in a  OS image at a mirror site:
> 
>
http://ringtail.its.monash.edu.au/pub/fedora/linux/releases/8/Fedora/i386/os/
> 
> ERROR:
> Unable to find image at given location
> 
> This is the only approach which creates a VM, but the machine is not 
> completely running (not functional or doesnt consume any memory). Am I 
> supposed to have the guest image on my machine?
> 
> 
> *3. Using "virt-manager" in GUI*
> 
> ERROR: Asks for "Connect to host  network" *but "shared
physical
> devices" list is empty*. It is supposed to list eth0, peth0 etc. 
> Something to do with creating a bridge. I tried the approach of NAT, but 
> for that I have to use approach 1 to create a machine, which gets stuck 
> on "root" error.
> 
> 
> Libvirtd is not running. It gave the message:
> 
> libvir: Remote error : Connection refused
> libvir: warning : Failed to find the network: Is the daemon running ?
> libvir: Remote error : Connection refused
> 
> xend is running, I checked status.
> 
Commenting on method 2:

If you have got a iso of F8 DVD somewhere, mount it loopback on 
/var/www/html/pub & start your web server

# mount -o loop F8.iso /var/www/html/pub
# service httpd start

Then you should be able to do the installation

          # virt-install \
               --paravirt \
               --name demo \
               --ram 500 \
               --file /var/lib/xen/images/demo.img \
               --file-size 6 \
               --nographics \
               --location http://ip of your web server/pub


Good luck.
Olivier

Thanks for your advice Fajar. I will definitely consider it, but I have very
close deadlines to achieve (get guests up and running by the end of this
month) and am worried about facing similar system problems again. I hope
that I do not lose more time in those. Is there an active community around
using Centos/RHEL which can help me? I was very disappointed with the
Fedora-Xen community.


Thanks & Regards,
Siddharth Wagh
-----------------------------------------------------------------------------------------
To ensure perfect aim, shoot first and call whatever you hit the target...
-----------------------------------------------------------------------------------------


On Thu, Feb 12, 2009 at 8:38 AM, Fajar A. Nugraha <fajar@fajar.net> wrote:
> On Thu, Feb 12, 2009 at 4:32 AM, Siddharth Wagh
> <siddharth.wagh@gmail.com> wrote:
> > I am not
> > comfortable with kernel administration/OS admin
>
> In that case I suggest you switch to Centos 5.2 (or RHEL 5.3, if you
> can afford it), choose virtualization support during installation, and
> try again. Manual is available on
>
>
>
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualization_Guide/index.html
>
> or
>
> http://www.centos.org/docs/5/html/5.2/Virtualization/
>
> Regards,
>
> Fajar
>

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On Fri, Feb 13, 2009 at 4:16 AM, Siddharth Wagh
<siddharth.wagh@gmail.com> wrote:
> Thanks for your advice Fajar. I will definitely consider it, but I have
very
> close deadlines to achieve (get guests up and running by the end of this
> month)
Which is why I told you to use RHEL/Centos :)

Seriously. I could write a loooong response about what went wrong with
your install, but to be honest a lot of things could cause that. And
you didn''t exactly give much helpful information (like what the
contents of vm01-config.sxp is). As for virt-install and virt-manager,
I''m guessing both failed because somehow your xen network config is
messed up that the domU can''t connect to the mirror site.

Another point to consider is that Centos/RHEL5 is actively maintained
while Fedora 8 has reached EOL and Fedora 9/10 doesn''t support xen
dom0.

Considering all that, the fastest route would be to start from scratch
with RHEL/Centos 5.2 or 5.3, selecting "Virtualization" package from
start.  Note that you should start with AT LEAST Centos 5.2, as there
have been lots of bug fixes (including xen-related ones) after the
initial 5.0 release. With the default installation, the Virtualization
Guide should be able to help you get a domU running with minimum
effort. This howto should also do the same thing
http://www.howtoforge.com/centos_5.0_xen

If you were an experienced sysadmin I could give you a different advice :)
> and am worried about facing similar system problems again. I hope
> that I do not lose more time in those.
If you''re in a "I must get this to work no matter what"
situation then
its probably to find help from your local sysadmins to give you
hands-on support. Mailing lists aren''t exactly a replacement for good
technical support.
> Is there an active community around
> using Centos/RHEL which can help me?
Many people on this list use Centos/RHEL.
> I was very disappointed with the
> Fedora-Xen community.
>
Probably because Fedora8 has reached EOL.
And probably because you''re asking about basic things already covered
in existing documentation, so the common response would be "RTFM"

Regards,

Fajar

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hi,

2009/2/13 Fajar A. Nugraha <fajar@fajar.net>
> Guide should be able to help you get a domU running with minimum
> effort. This howto should also do the same thing
> http://www.howtoforge.com/centos_5.0_xen

One more good howto.
http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU

-- 
Regards,

Meghanand N. Acharekar
" A proud Linux User "
Reg Linux User  #397975
------------------------------------------
I was born free! No Gates and Windows can restrict my Freedom !!!


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