We run KVM on all of our current machines (about 20-25 VMs at any given time), managed by Cloudmin (eating our own dog food). Before that, it was Xen, which als

We run KVM on all of our current machines (about 20-25 VMs at any given time), managed by Cloudmin (eating our own dog food). Before that, it was Xen, which also worked well. The decision is mostly one of least resistance; KVM has the best out of the box support on CentOS 7, so it's what we're using. Back when Xen met that description, we used Xen.