Could Server Sprawl be a problem? by Peter Judge

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Peter Judge

Could Server Sprawl be a problem? by Peter Judge

Ever moved house, and packed up junk in boxes, because it’s easier than sorting it out? Or had other people pack that junk up for you? Years later, that junk will still be there in boxes, taking up room in your garage.

Apparently the same happens to data centers, when they go on the big trek to virtualisation. When IT managers virtualise their servers, 65 percent of them will pack up a whole bunch of servers that are not even being used, and carefully reinstate them as virtual machines in the new virtualised infrastructure or company cloud.

That’s according to Andy Hawkins of power management company 1E, a firm whose Nightwatchman product keeps a watch on power use by servers and desktops - and which is now spreading its reach into the power use of virtual servers.

But what’s the big problem with virtual machines? People virtualise so they can cut down on the number of physical servers they have, and after that, new VMs are pretty much free, after the minimal overhead of running a hypervisor, I always thought.

If a VM isn’t doing anything you can park it to disk. If it’s not doing much, then the physical server is available for the other VMs it is hosting. It’s not like a whole piece of hardware cluttering up a room.

Users are aware that they are running lots of virtual machines, but most don’t see it as a problem. I spoke with one user who told me he started out with about twenty servers. Since virtualising, he now has around 200 VMs - but he is saving plenty on energy, because he is running those VMs on only six physical servers and he has no plans to expand that number. You can listen to the conversation here.

Many of his VMs are for tests, and only get fired up when he wants to try a new build of an application. What’s the problem?

Hawkins reckons the problem is unaware users who have got rid of their server sprawl, and replaced it with virtual server sprawl - simply because they can’t tell whether a server is doing real work or not.

Most people just check if there’s any CPU activity, but you can have servers which are chugging away quite busily, running maintenance tasks and anti-virus jobs, but not doing any real work at hall, says Hawkins.

These can get virtualised along with the rest, unless you can check if they are doing “real work” (which, as you’ll have guessed, 1E’s product claims to do).

Unused virtual machines do have a cost - in disk space, and in the server power they use when they are running. “There is a feeling that virtual machines are free,” said Hawkins, “but they use energy, need an OS licence and application licences and have a labour cost.”

That’s all useful in the process of de-cluttering the server room.

I’m hoping it will inspire me now, because when I get home this evening, I’m being sent to the attic, to de-clutter fifteen years’ worth of my junk. In a couple of weeks’ time, I am moving house.