At Fri, 27 May 2011 14:33:23 -0400 (EDT) CentOS mailing list centos@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.