On Sun Apr 12, 2009 at 21:21:26 +0100, Brian Chivers wrote:
> I'm starting to look at virtualisation but I know very little about it.
> I've read a bit about Xen & KVM and have had several companies visit
> College drumming on about VMWare (very expensive but nice features) & M$
> HyperV(quite cheap for education). I would really like to stay open
> source but I need to read more about this as it'll be for "business
> critical" systems so stability, flexibility and easy management will be
> very important.
The management is where most of the open solutions fall down.
Your choices are probably going to be:
uml - obsolete
xen - heavyweight. waning support.
qemu/kvm - fast. regular updates.
vmware - closed source. good reputation
openbox - ?
UML is only useful for hosting Linux guests on a Linux host, and
while it has performance problems it is very stable and simple to get
started with.
Xen is an oddity - at one point it looked like it was going to take
the world by storm. Since it failed to get integrated into the
mainline kernel it has suffered a lot, and to be honest these days I'd
ignore it as a stagnant irrelevancy.
KVM builds upon the stunningly featureful Qemu software, and adds a
kernel-based driver which boosts performance. It is very easy to get
started with, and has the bonus that if you're running a recent kernel
you probably have over half the software you need already present.
VMWare have made a lot of their lower-end software available for
free, but it isn't open source. If you only one one-ten guests then it
works very well, but if you want to use it heavily you're going to miss
the nice admin tools they have - as they're still commercial.
Openbox I've never used, so I cannot comment. But people do say nice
things about it.
In short if you don't care about the closed nature then VMWare has
always had a nice reputation, and if you want to be open-source
friendly then I'd strongly recommend KVM. (Or openbox; can't recommend
it as I've never tried it.)
In all cases though your biggest problem will be the admin side, tools
to create, manage, control, and copy the guests are lacking in the open
world.
Right now, for example, my KVM guests are running inside GNU Screen
which is functional but hardly very attractive. Still for most of the
basic tools kvm, qemu, lguest and uml the basic process is very
similar:
1. Create a volume "dd if=/dev/zero of=path/to/disk.img bs=1024 count=8192k"
2. Launch the software pointing at the virtual disk
kvm -hda /var/kvm/etch64.security.build.img ...
3. Setup appropriate networking support.
Each of these operations is very well documented, so you probably
don't need a book. Just pick one of the packages and read the
documentation. (VMWare/OpenBox are more GUI applications so you might
try those first if you're hazy on the command line stuff.)
Steve
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