Five power-saving tips for maxed-out datacenters

By Rick Vanover | May 6, 2011, 2:58 PM PDT

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.
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