Best Practice: bind, dhcpd, mysql, httpd, etc running on KVM Host?

Question

With respect to "Best Practice" when it comes to virtualization, is it advisable to run services such as bind and / or dhcpd on a KVM host or should these services be run from a guest machine?

How about mysql or httpd? Basically, can the host machine be used as a functional system for, perhaps, more i/o intensive services thereby bypassing the virtual layer?

I can see advantages for both scenarios. I'd like to know what would be considered best practice regarding virtualization.

Answer 1

Best practice: Don't run anything but the hypervisor on the host.

Answer 2

basically, yes, you can run other services on a KVM host, however, that means the VMs, a pretty heavy service on their own, will have to share resources, in an uncontrolled manner, with other applications. Not nice if you overcommit RAM and end up swapping, for example