Running Xen on low spec single CPU

[Adrian Revill]

I know a lot of people just see Xen as a method to use over spec'd boxes 
more efficiently, but im interested in using its virtulisation 
capabilities on low  spec systems.
Has any one had any luck with getting a DomU running on a single CPU.

I seem to get stuck during the install, as far as i can see it seems 
that the DomU is not being allocated CPU time.

Using Fedora 6, i can get through the anaconda stage in about 1/2 hr but 
when the X window starts the CPU use drops to near 0% and i never get 
past a black screen with the X cursor.

[Adrian Chadd]

On Mon, Feb 26, 2007, Adrian Revill wrote:
> I know a lot of people just see Xen as a method to use over spec'd boxes 
> more efficiently, but im interested in using its virtulisation 
> capabilities on low  spec systems.
> Has any one had any luck with getting a DomU running on a single CPU.
>
> I seem to get stuck during the install, as far as i can see it seems 
> that the DomU is not being allocated CPU time.
>
> Using Fedora 6, i can get through the anaconda stage in about 1/2 hr but 
> when the X window starts the CPU use drops to near 0% and i never get 
> past a black screen with the X cursor.

I have no trouble with Xen on single CPU athlon machines running >10 DomU's.
I don't run X or a framebuffer console. And my IO load is light.

Adrian

[Adrian Revill]

Hi Adrian,

Thx for the reply, gives me hope. As you can guess im new to Xen.

So how do you install the os into the DomU?
If i was installing from cd i could use linux text expert, but i cant 
see how to give the option to the Dom install.

regards
Adrian

Adrian Chadd wrote:
> On Mon, Feb 26, 2007, Adrian Revill wrote:
> > I know a lot of people just see Xen as a method to use over spec'd boxes 
> > more efficiently, but im interested in using its virtulisation 
> > capabilities on low  spec systems.
> > Has any one had any luck with getting a DomU running on a single CPU.
> >
> > I seem to get stuck during the install, as far as i can see it seems 
> > that the DomU is not being allocated CPU time.
> >
> > Using Fedora 6, i can get through the anaconda stage in about 1/2 hr but 
> > when the X window starts the CPU use drops to near 0% and i never get 
> > past a black screen with the X cursor.
>
> I have no trouble with Xen on single CPU athlon machines running >10 DomU's.
> I don't run X or a framebuffer console. And my IO load is light.
>
> Adrian

[Adrian Chadd]

On Mon, Feb 26, 2007, Adrian Revill wrote:
> Hi Adrian,
>
> Thx for the reply, gives me hope. As you can guess im new to Xen.
>
> So how do you install the os into the DomU?
> If i was installing from cd i could use linux text expert, but i cant 
> see how to give the option to the Dom install.

I bootstrap Debian/ubuntu in a fresh jail using debootstrap inside the
install root. I dump that into a freshly made LVM partition and boot
the DomU up, then finish configuring it that way.

Its not that simple. :) I'm pretty sure there's a much nicer way
to bootstrap Fedora DomU's and hopefully one of the Fedora-Savvy people
'ere will point it out.

Adrian

[John Summerfield]

Adrian Chadd wrote:
> On Mon, Feb 26, 2007, Adrian Revill wrote:
> > Hi Adrian,
> >
> > Thx for the reply, gives me hope. As you can guess im new to Xen.
> >
> > So how do you install the os into the DomU?
> > If i was installing from cd i could use linux text expert, but i cant 
> > see how to give the option to the Dom install.
>
> I bootstrap Debian/ubuntu in a fresh jail using debootstrap inside the
> install root. I dump that into a freshly made LVM partition and boot
> the DomU up, then finish configuring it that way.
>
> Its not that simple. :) I'm pretty sure there's a much nicer way
> to bootstrap Fedora DomU's and hopefully one of the Fedora-Savvy people
> 'ere will point it out.

Debian/Ubuntu has some nice scripts for creating VMs (a little buggy at 
present though).

It writes the xen config file, and (according to its docs) can create 
Ubuntu, Debian and Fedora guests, is extensible. It has the option of 
running debootstrap (for Debian/ubuntu), rpmstrap (for RPM-based 
systems), creating the system from an exising directory tree, from a 
tarball.

With the right incantation, you can go from raw materials to a running 
guest in one command.

SUSE's Yast cam also create guests; I have a SLES guest on my laptop 
(openSUSE 10.2 host) created with Yast.

[Markus Armbruster]

Adrian Revill  writes:
> I know a lot of people just see Xen as a method to use over spec'd
> boxes more efficiently, but im interested in using its virtulisation
> capabilities on low  spec systems.
> Has any one had any luck with getting a DomU running on a single CPU.
>
> I seem to get stuck during the install, as far as i can see it seems
> that the DomU is not being allocated CPU time.
>
> Using Fedora 6, i can get through the anaconda stage in about 1/2 hr
> but when the X window starts the CPU use drops to near 0% and i never
> get past a black screen with the X cursor.

Shot from the hip: how much physical RAM?  How much memory allocated
to the domU?

[Daniel P. Berrange]

On Mon, Feb 26, 2007 at 08:32:18AM +0000, Adrian Revill wrote:
> I know a lot of people just see Xen as a method to use over spec'd boxes 
> more efficiently, but im interested in using its virtulisation 
> capabilities on low  spec systems.
> Has any one had any luck with getting a DomU running on a single CPU.
>
> I seem to get stuck during the install, as far as i can see it seems 
> that the DomU is not being allocated CPU time.
>
> Using Fedora 6, i can get through the anaconda stage in about 1/2 hr but 
> when the X window starts the CPU use drops to near 0% and i never get 
> past a black screen with the X cursor.

How much RAM did you give the guest install VM - RAM is much more important
than CPU speed - I've seen hangs like the one you describe when I didn't
give enough RAM for install.

Dan.

[Adrian Revill]

Hi Dan

I have a 1.7+ XP athlon and 1.5G ram in the box an have given it 512Mb 
for the DomU

The same settings work a treat on a quad core Opto
> How much RAM did you give the guest install VM - RAM is much more important
> than CPU speed - I've seen hangs like the one you describe when I didn't
> give enough RAM for install.
>
> Dan.

[Frank Rosendahl]

Am Montag Februar 26 2007 schrieb Adrian Revill:
> Hi Dan
>
> I have a 1.7+ XP athlon and 1.5G ram in the box an have given it 512Mb
> for the DomU
>
> The same settings work a treat on a quad core Opto
> > How much RAM did you give the guest install VM - RAM is much more
> > important than CPU speed - I've seen hangs like the one you describe when
> > I didn't give enough RAM for install.
> >
> > Dan.
>
> --
> Fedora-xen mailing list
> [e-mail]
> https://www.redhat.com/mailman/listinfo/fedora-xen

I use a Double Pentium III 650 MHz with 1GB RAM with 3 DomU's running.

It's really good running!