I am not convinced that virtual machines are the way to go for production environments. Yes, it saves costs in hardware, cooling systems, and power. But it places another layer of complexity in the system and provides another place to play the blame game and point fingers at when production systems fail.

I was part of a team that developed and supported a system that ran on several dedicated servers. Virtual machines were added to the mix to expand the system and distribute the workload. AHBL (All Hell Breaks Loose) happened after the VM systems were added. The systems running on the virtual machines crashed at least once a day, sometimes more than once a day! It turns out that the anti-virus running on each virtual machine was causing the production system to crash. Now, these systems were behind the firewall, not connected to the outside world, and had no access to email. The solution for system stability on the VM systems? The networking and infrastructure support group turned off the anti-virus.