I installed my first production virtual server host over a year ago using a product called ESX Server by VMWare. Simply put, it is awesome! I have had four moderate use file servers running off of this virtual server, for about 1500 users in all running on this with abosolutely no problems. The virtual machines were Windows Server 2003, and I kid you not, only one server out of the bunch had to be rebooted in a years time. That is what I call low-maintenance and reliable!
ESX Server is an impressive peice of software. The host machine basically runs a razor-thin vesion of linux tuned for running virtual machines, and it gives each VM direct access to hardware, which translates into near-standalone performance, given the other VM are not hogging those same resources at that given moment. I’m running this current setup using a Dell PE2850, 2-way dual-core Xeon chips, and 8 gigs of RAM. Performance has NOT been an issue at all. I’ve just installed a new ESX server this week, also running 4 VMs, but this server has 2-quad core Xeons and 16 gigs of RAM. I was tempted to see how well this machine would run Supreme Commander, but you know……. I don’t get paid for that 🙂
VMWare Server, the free version, is also a very worthy program. If you are not buying all of the addons that are available for ESX Server such as VMotion and VirtualCenter (which I *HIGHLY* recommend you do!), then VMWare Server and ESX Server are very comparable in terms of features. The main difference of course, is that VMWare Server uses Windows Server as it’s host OS, and performance-wise it can’t hold a candle to ESX. I’ve been using Server in several locations now in production for hosting web servers, log server, and light duty file servers, with absolutely no problems.