Re: some virtualization issues/comments (qemu,uml)
Quoting Benedict Verheyen <benedict.verheyen@sjki.be>:
> Hi,
>
> I've been looking into UML and qemu for virtualization and testing
> distro's and features.
>
These are both good choices each with specific advantages/disadvantages.
> It seems to me that qemu is a nice way to testdrive a distro, upgrading,
> checking a new kernel (an issue i've been having with an upgrade from
> a woody to a sarge release), testing backups (restore). Even some
> proprietary OS runs on it (if that's an advantage, i'll leave that up to
> you :))
For some of us that require use of said propritary OS (for things such as work/
gaming), it is an advantage :-) Though, it will be nice when one day even that
need has vanished.
> Qemu is also extremely easy to setup.
>
I agree. A while back I tried out bochs (as an alternative to VMWare) and
found
it clunky, poorly documented, and difficult to use. The only thing I managed
to get running in bochs was Minix. Then, only because Andy Tanenbaum makes a
bochs image with Minix preloaded on it available. I managed to barely get
Woody installed inside of bochs, but never anything else.
> UML on the other hand seems faster and more suitable to sharing a
> machine and giving each person his/her own UML to mess with.
> What i'm planning to do in the future for my home lan is making a few
> UML's on my current server to provide different hosts for DHCP,DNS, mail
> and webserver. I can't see this happening with qemu because it would
> probably be a bit to slow.
>
Fabrice Bellard, primary developer of qemu, has recently released a binary-only
kernel module for 2.4 or 2.6 kernels on x86 that provides much better
performance. It does this by using virutalization (instead of the full-blown
emulation that qemu normally uses). This means that it gets much greater
performance, but at the cost of only being able to run x86 binaries on x86
hardware.
> I haven't played with Xen or vservers yet.
>
Neither have I. Though, I have heard that for some roles where UML is being
now, such as virual server hosting, it better suited because of its ability to
manage the multiple systems.
> Does anybody know if it's possible for UML to install a distro from a cd
> like you can do with qemu? That way you can really test the setup of a
> distro. For instance, one could test the debian installer.
>
Not sure on this. I believe that as long as you have a UML kernel image, you
can use it and ask the UML instance to boot from which ever device you like.
You would likely need to get the source of the CD from which you are going to
boot and compile it with a UML patch to make this work, though.
> Both for UML and Qemu what would be an good way (=easy setup) of sharing
> the package cache of the host? Ideally that would be something that can
> be used by other hosts on the LAN too.
> I'm currently having a look at apt-move
>
apt-proxy. Very easy to setup. Comes preconfigured with quite a few official
repositories and some unofficial ones (like backports.org). The only thing is
that is only in Woody (old version) and Sid (new version that is not ready for
release in Sarge).
> Thanks for any remarks/comments
>
You are quite welcome :-)
> Regards,
> Benedict
-Roberto
--
Roberto C. Sanchez
http://familiasanchez.net/~sanchezr
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