Data Centers

Five power-saving tips for maxed-out datacenters

If your office or datacenter is about to exceed its power capacity, these strategies will help you reduce consumption and use power more efficiently.

We all deal with some form of datacenter or office that is at the brink of power capacity. I can't tell you how many times I bump into situations where a computer room can't accommodate another server or storage device -- let alone deliver enough cooling capacity -- due to lack of available power in the facility. Over the years, I have discovered a few tricks to save power.

Note: These tips are based on an entry in our Network Administrator blog.

1: Virtualize

There is no single more effective power reduction strategy for the datacenter than server virtualization. While the hosts (VMware ESXi or Microsoft Hyper-V) may be larger and consume more power per server unit than traditional physical servers, high consolidation ratios can lower the average power consumption per server.

2: Consider group policy objects for PCs

In modern versions of Active Directory, Group Policy configuration can set the power plan by policy. This is located in Computer Configuration | Preferences | Control Panel Settings | Power Options. There, power plans for Windows XP and later systems can be set for computer accounts and delivered without risk of user tampering. Be sure to see Katherine Murray's tips on power-saving strategies for PCs.

3: Ditch the KVM and monitor in the datacenter

I've started to think we're beyond the KVM (consolidated keyboard, video, mouse controller) and monitor, even if shared for a large number of systems in the datacenter. I'm much more in favor of leveraging hardware controllers, such as the HP iLO or Dell DRAC. Should there be systems without those controllers, you may want to create a "crash cart" that has a small LCD screen, keyboard, mouse, tools, and other miscellaneous handy things. If you're considering a new server purchase and are on the fence about the extra cost for the iLO or DRAC, I recommend you get it and take the time to get familiar with these tools, if you are not already.

4: Idle any excess capacity

Frequently, network switches may be overprovisioned in terms of ports for the entire datacenter. Considering that virtualization ideally reduces the overall port consumption requirements, it may be worth a recabling party to consolidate remaining switch ports to active switches and turning off (but not necessarily decommissioning) any switches with no used ports.

5: Consolidate

Bottom of rack UPS units are hard to manage, especially if all the batteries in the facility are on separate battery replacement cycles. During the next procurement cycle or battery replacement initiative, it may be time to put in smaller units to reflect actual consumption rather than having a larger battery remain charged and consuming facility power for a rack that will never be more than 30% full in terms of servers.

If virtualization or new battery units are not an option, it may be high time to move from six racks that are 30 percent full to two racks that are fully populated. This can make all the components in the rack (PDU, KVM, UPS, etc.) fully utilized as well as the space of the rack.

Also, like UPS units and KVMs, PDUs will be consuming facility power even if there are no servers or computing devices connected to them. Again, consolidation of these devices may be a good power conservation strategy.

Bonus tip: Consider blade servers

If a large batch of servers is up for replacement, will blade servers do the trick? They may require a special power supply (three-phase or 30 amp interface), but power consumption per server may be lower than a typical replacement. Another option is deploying mini-blade servers, which can save space and possibly reduce power.

More tips

What power-saving tricks have you employed in your datacenter or for your PCs? Share your comments below.


Rick Vanover is a software strategy specialist for Veeam Software, based in Columbus, Ohio. Rick has years of IT experience and focuses on virtualization, Windows-based server administration, and system hardware.

Rick S._z
Rick S._z

#1. Many middle-aged rack Servers are built with PSUs which are only 75% efficient. Often, the PSU is replaceable. (Big savings in direct power costs, PLUS a reduction in waste-heat generation.) #2: If you're alternative is a huge investment (new power wiring; new cooling) maybe escape from the entire nightmare of "One UPS per Rack"? And also consider moving the configuration into DC power distribution. (Change the AC->DC->AC->DC process into one of AC->DC just once. Battery and Flywheel-based UPS units are running DC internally, and waste some power by converting it back into AC -- only to be converted back into DC by the Server PSU.) But #1 is bigger: middle-aged equipment is often only 60-70% efficient end-to-end, and replacing older, inefficient Server PSUs and Rack UPS components can move you up to about 80% efficiency. That's a big difference- you might be cutting the waste in a current situation of "40% Wasted As HEAT" by **HALF**.


Cooling energy requirements (and costs) can be reduced 30-55% in most data centers. Look for: - incorrect row directionality - cascading equipment exhausts - recirculation within cabinets - blow-by at the rack bottom - uneven air flow - hot spots - air short-circuiting - leaky raised floors - hot and cold air mixing - humidity instability - improperly regulated reheat circuits - limited capacities - improper set-points - comfort cooling vs. process cooling The guy who used to be Google's data center architect started Precision Air and Energy Services. (Disclosure: I'm not affiliated with PA&E, but the founder is a former coworker, friend, and IMO genius at HVAC.) In a typical data center they reduce energy costs 30-55% via precise air flow control and variable water/glycol flow. They also train staff to keep everything in balance after they're gone.

Rick S._z
Rick S._z

I focused on the electrical. Between our two posts, someone can learn a lot. :))

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