Re: [SLUG] UserMode Linux

From: Ian C. Blenke (icblenke@nks.net)
Date: Tue Apr 29 2003 - 09:39:02 EDT


On Monday 28 April 2003 17:46, Kwan Lowe wrote:
> Has anyone here used UserMode Linux before? I'm trying to setup a
> virtual machine to host my web site in the event that the main, physical
> box goes down. So far I've been experimenting with some VMWare options,
> but I've been having lots of difficulty with later versions of Linux
> (RH9, Mandrake 9.1).

We're running hundreds of UML images at NKS, and I'm now running them on every
physical linux box I own (including the firewall - which is a story into
itself).

> The main goal is to be able to have a drop in replacement for the
> physical box. As it is now, I have a DSL router port forwarding http
> requests to a private IP. If the server goes down I would like to start
> the UML instance on my desktop workstation until I can rebuild the
> server.

Then you're probably going to want to use a linux bridging interface (ala
"brctl" from bridge-utils) to bind your workstation's eth0 to your UML's tun0
(or whatever you may have named it), ie:

        ifconfig eth0 0.0.0.0
        ifconfig tun0 0.0.0.0
        brctl addbr br0
        brctl addif br0 eth0
        brctl addif br0 tun0

Then bring up your workstation's br0 interface as if it were your eth0
interface. On your UML guest image you should be able to use eth0 as if it
were on the same physical segment as your physical server and workstation.

> I've almost gotten it working in VMWare, but there are a few problems:
> E.g.: RedHat 9 installation went fine but ran into SIMD errors on the
> initial kernel boot. I was able to get around these by rebuilding a
> kernel without athlon/SIMD specific optimizations and checks. OpenSSL
> also had major problems and I needed to replace the i686 package with an
> i386 version. Apache wouldn't start for an unknown reason.

All very odd. I've not run anything Mandrake post v7 or so. There may be
kernel headaches I'm unaware of trying to run under VMWare.

The "easiest" way to make a UML Mandrake 9 image would be to use UMLBuilder:

        http://umlbuilder.sourceforge.net/

Grab the RPMS and follow the instructions. It's actually rather painless on an
RPM based python friendly distribution (getting it to run on Debian isn't
trivial, particularly for a beginner).

Gah, I still need to *make time* to finish the damn recorded UML VNC session
guides. So many things to do, so little free time.

-- 
- Ian C. Blenke <icblenke@nks.net>

(This message bound by the following: http://www.nks.net/email_disclaimer.html)



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