Network World — Millions of servers around the world are doing little more than wasting energy, according to a new study.

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At least 15% of servers are not doing anything useful, said a majority (72%) of server managers polled by Kelton Research. In addition, 83% said they don't have an adequate grasp of server utilization, and 72% rely on CPU utilization as their measure of server efficiency.

The cost of unused servers is estimated at $24.7 billion a year, including the value of hardware, maintenance, management, energy and cooling for unused servers.

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Specifically, the study concludes that an estimated 4.75 million servers worldwide are being run 24/7, managed and upgraded without being actively used on a daily basis. Assuming about $4,400 per server per year in operational costs (an IDC estimate), those unused servers cost $20.9 billion to run, plus consume another $3.8 billion in energy costs.

The study was conducted in September and commissioned by 1E (a vendor that offers software and services to help reduce enterprise IT costs and energy usage) in association with the Alliance to Save Energy.

"Very few data center managers or server managers are focused on decommissioning or getting rid of the servers that aren't actually doing anything useful," says Sumir Karayi, CEO of 1E.

Companies want to pay more attention to server efficiency and energy management, but they lack the tools and processes to do so, he says. For example, many rely on CPU utilization to gauge a server's usefulness, but that's a flawed approach.

"The problem with CPU utilization is that a server could be busy doing its housekeeping tasks, such as its own antivirus scans, its own backups, its own indexing and defragmenting of hard disks," Karayi says. "It will look busy, but it's not actually adding any business value."

The study found more than half of server managers (63%) rely on manual checks, trial and error or wait until something is broken to find unused servers. In addition, 75% admit that their companies' mandates to deliver high levels of IT service internally get in the way of measuring and improving server efficiency.

1E's release of the study results coincides with its launch of its tool for monitoring server usage. NightWatchman Server Edition provides metrics around server efficiency and power usage to help companies determine which assets aren't being used and can be decommissioned.

The software can conduct a work analysis to determine how much useful work a server is performing, the energy it's consuming and whether there is any waste, for instance. With the Drowsy Server feature, IT administrators can opt to have idle servers put in a "drowsy" state that reduces energy consumption but doesn't impact a server's availability, Karayi says.

"Drowsy enables a server manager to make a server consume less power when it's not doing useful work,' he says. "We're not making the server go into a standby or sleep state. The server is still working, it's just running a bit slower."