Hypervisors and you!

Joseph Hall perlhoser at gmail.com
Fri Mar 15 08:30:47 MDT 2013


On Fri, Mar 15, 2013 at 8:12 AM, Tod Hansmann <plug.org at todandlorna.com> wrote:
> - I'm looking at Xen, but don't know much about it yet

I haven't heard of anyone lately that has started using Xen since KVM
got popular. The VM world, in my limited view, does seem to be moving
away from Xen.

> - KVM isn't going to be a whole lot better with regards to management
> unless I use something on top of it.  My only OTHER issue with KVM is
> that it seems I will have to install a full OS of some sort, when I'd
> rather just have a bare metal Hypervisor.  Correct me if I'm wrong, I
> guess, but managing the thing is important, too.

This discusses the differences between Xen and KVM:

http://www.linux-kvm.org/page/FAQ#What_is_the_difference_between_KVM_and_Xen.3F

It should be noted that Xen is technically its own OS (albiet an
extremely light one) that Linux sits on top of. You still need a
normal Linux install running Dom 0, but unlike KVM, you can
paravirtualize the guests sitting on top of Dom 0.

There are both performance improvements and security concerns involved
in running paravirtualized machines. If you're going to go that route,
you might want to look at OpenVZ or LXC (which is supposedly "OpenVZ
done right). Ultimately, I think the task at hand will dictate whether
you go with full or paravirtualization. What services will you be
running? What kinds of and how many users will have access to these
machines? What resources (outside of the hyper itself) will be shared,
if any? These will all come into play.

> - Last but not least, I'm concerned about upgrade ability.  I'm going to
> put this in my colo, and I do NOT want to break things with an OS
> update.  I'd rather enjoy uptime of about 3 years before having to go
> back to the colo.  I guess what I'm saying here is I will never use
> Gentoo in this case.

Or Arch. I love it to death, but I have worked with it in production
(on hypervisors running KVM), and it was insane. Next time I will go
with one of the RHEL variants (have you looked at The GoOSe Project?).
Stick with an enterprise or LTS distro and you should be fine, so long
as you don't try to introduce any software much newer than the distro
you choose.

-- 
"In order to create, you have to have the willingness, the desire to
be challenged, to be learning." -- Ferran Adria (speaking at Harvard,
2011)


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