Improving Hosting: 4. Virtualization

There are some downsides to Virtualization. It introduces an extra level of indirection between the OS and the hardware layer, so it has some impact on performance. For example, while many people use virtualization for web servers, the approach is not necessarily recommended for dedicated database servers which can show a noticeable performance hit from the extra layer between the database software and the hard drive.

There are also plenty of benefits. Talking with hosters that use virtualization widely, the benefit almost everyone agrees on is that having a pre-configured image makes it MUCH quicker to provision a server as you don't have to install and configure the OS and applications - you just get one image built and then copy the image to the machine. Of course, building a completely new machine still requires configuring a base OS unless you use something like the GSX product from VM Ware which allows for quicker and easier provisioning of servers - but at a cost of having to run approved hardware and pay about $1,000 for the software per server. The base VM Ware product is free, but with its requirement to configure a base OS manually and the lack of support for things like live backup images of running machines, it is a trade off. Of course there is also the benefit of being able to consolidate multiple lightly loaded physical servers into a single machine, so if you have a number of apps that need to be on different "servers" but don't need the whole power of the server, virtualization is an obvious solution.

Clearly with enough servers, virtualization pays for itself very quickly. The same if true if it allows you to consolidate multiple servers or if you have complex configurations required to get your OS running. What I'm trying to decide now is whether it makes sense to go with something like VM Ware for our hosting needs.

My issue is that I need multiple physical servers for redundancy purposes, but I don't have that much load, so I'm tempted to use a handful of $2000 SuperMicro machines with mid level specs (they've served us well to date). From a load perspective we could probably run all of our clients on a single web server and single database server at the moment, and as we port all of our projects to the latest version of our software it is very easy for us to run them all as shared sites on a single physical or virtual server, so we really don't need virtualization for the consolidation benefits.

From input to date I get the impression that we probably "should" be using Virtualization, but with a relatively small number of servers and the fact that we're going to have to install the base OS anyway on each new box, I'm wondering how much provisioning time VMWare would really save us if we're only planning on bringing onstream say 3-4 new servers a year.

I'd really appreciate any input from people who have used the free version of VM Ware in production. How has it worked out for you? Any unanticipated problems? What benefit did it end up providing? Any unexpected upsides? What was the learning curve? Is it worth the effort?!

Any input much appreciated!