[CentOS] OT: Why VM?

Fri May 27 19:35:19 UTC 2011
Robert Heller <heller at deepsoft.com>

At Fri, 27 May 2011 14:33:23 -0400 (EDT) CentOS mailing list <centos at centos.org> wrote:

> I have been working off and on with Xen and KVM on a couple of test
> hosts for that past year or so and while now everything seems to
> function as expected, more or less, I find myself asking the
> question: Why?
> We run our own servers at our own sites for our own purposes.  We do
> not, with a few small exceptions, host alien domains.  So, while
> rapidly provisioning or dynamically expanding a client's vm might be
> very attractive to a public hosting provider that is not our
> business model at all.
> Why would a small company not in the public hosting business choose
> to employ VM technology?  What are the benefits over operating
> several individual small form factor servers or blades instead?  I
> am curious because what I can find on the net respecting VM use
> cases, outside of for public providers or application testing, seems
> to me mostly puff and smoke.

One of the benefits of VM over small form factor servers or blades is
ecomonies of scale: a 'larger' server box (larger == additional memory
and disk space, maybe more cores) might be cheaper than several
smaller, lower-end machines.  And given the way things are going in
terms of many core procssors, memory and disk prices, these sorts of
ecomonies of scale are going to increase -- it may stop being cost
effective (or even impossible) to get a 2-core box with 2-4 Gig and a
160gig disk and using a 6-core processor with 64gig of RAM and a 4TB
disk is insane for a *simple* web server, even if you are hosting a
couple dozen virtual hosts.

> This might be considered OT but since CentOS is what we use it seems
> to me best that I ask here to start.

Robert Heller             -- 978-544-6933 / heller at deepsoft.com
Deepwoods Software        -- http://www.deepsoft.com/
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