Should I Convert My Old Servers to ESX?

Frequently asked question: My company is virtualizing our data center. Should we buy new servers or turn the ones we have into ESX servers?

My usual answer is a question: “How old are the servers you have?”

Average answer: “Somewhere around three years old.”

My reply: “Get new servers.”

Why new servers? Because, performance-wise, they smoke your old servers, and have all the new technologies like Extended Page Tables, VT-x, VT-d, etc. RAM is often a limiting factor for how many VMs you can get on a physical host. Newer servers can have lots of RAM on them, more inexpensively than old servers can have lots of RAM on them. New servers often come with four NICs built in — two for the service console, two for VMs. Older servers have two. And with new servers you won’t have to worry about them again for five years until the warranty expires. Your old servers have two years left on their warranty and extended warranties are expensive.

In short, take a look at what you’d spend to retrofit and then replace your old machines and compare that with the cost of new equipment over three to five years. It might be worth it, but in most cases the old machines are just sunk costs.

6 thoughts on “Should I Convert My Old Servers to ESX?”

  1. But since many places are just now dabbling in virtualization, they may not want to step that deep into it at first. Remember that what you’re really paying for in virtualization is the licenses, so it may pay for them to get a proof of concept under their belt with their old equipment. Later they can migrate to newer servers with the same licenses and ditch the old equipment.

  2. If you’re dabbling you need to be clear about the potential performance differences between new hardware and old. I’ve seen one organization that thought virtualization had horrible performance because they were evaluating it on vastly underpowered gear. They actually decided to scrap the project based on that, and to this day think anybody virtualizing anything is making a huge mistake.

    Second, since the licenses do cost a significant amount of money it’s usually a good idea to get as much performance in as few sockets as possible. Again, if you’re fooling around that’s one thing, but if you are in any way serious about it ditch the old gear.

  3. Yes, people need to be aware the older hardware will not perform at the same level as the newer, but sometimes you don’t have the funds for newer hardware yet. A POC can loosen up those funds.
    Virtualization can be darn expensive compared to the hardware it will run on, so convincing people to spend the extra percentage of the project for the new hardware, “when we have perfectly good hardware here”, can be a challenge.

    Whoever is doing the POC needs to be clear about the performance expectations on the older hardware from the start. Communication is the key.

  4. @Alex — yeah, I saw that, and thought it was cool that you posted yours about the same time as I posted this. I’d put together a list of common questions I get about VMware and that just happened to be the one I posted.

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