A question came up recently on a mailing list I’m on about virtual machines for production applications. I’ve used virtual servers for web & database apps before, but only for dev/qa purposes. It made it much easier to go through deployment scenarios, try out new builds & roll back if the install failed, & generally avoid the time & money sink of dealing with setting up & maintaining actual physical machines. Plus virtual machines are easier to throw onto more powerful hosts as your needs grow.

However, if your organization is considering virtual machines for their production apps, they’re in growing company. Most of my experience with production apps has been to start with traditional shared hosting plans, then move up to dedicated machines. That approach works especially well if you only have a few web apps that can all run on the same machines, or if your CPU needs are high.

However, using virtual machines (aka virtual servers or virtual private servers) can be a good way to save money if you have a number of heterogenous and/or legacy applications that need their own “server” (for security, configuration, manageability, specific OS requirements, or other reasons) but don’t have very high horsepower needs. In that scenario, having a separate physical machine for each app can be costly overkill, and require you to answer repeated questions from your boss like “why did we need to buy and maintain 5 new servers when they’re all under 10% utilization?” 

Instead, you can have each app on its own virtual server, and put them all on one or more physical machines — however many are needed to run the apps effectively. Costs are reduced since you have fewer machines to power, watch, store, and maintain. Scaling applications can be simplified since you can allocate more or fewer resources to specific vitual servers, and you can always move them onto other, more powerful physical machines as your needs grow. Plus, disaster recovery can be easier, since if you have a hardware failure, you can just load the virtual server onto a different machine and keep on truckin’.

VMWare has some good info on their site: http://www.vmware.com/solutions/home.html

So does XenSource (Xen is open source virtualization software) http://www.xensource.com/solutions/ 

And I might as well link to MS Virtual Server, which apparently is free(?) 🙂 http://www.microsoft.com/windowsserversystem/virtualserver/evaluation/vsoverview.mspx

Plus there are some other links around the web if you search on “virtual server” or “virtual private server.”