Data center energy savings: be realistic

Data center energy saving is a hot news-item. Google announced experimenting with floating data centers in the sea, Sun is building a data center in an old coal mine below the surface which saves 50% on energy. Although energy reduction is a must, it is important to be realistic in the options available.

EvoSwitch, the hosting facility we use, has a Power Usage Effectiveness of 1.6 (yearly). Traditional (and most) data centers have a PUE of around 2.0. Their goal is to have a PUE of 1.2, something Google claims to have already.

Different business, different options
Google and others have completely different business cases then data centers like EvoSwitch. The way they manage their data centers differ completely from the way we have to. Restrictions on accessibility by clients, being carrier-neutral network data center and more, matter less for data centers Google is running, than a multiple client data center (our clients cannot take the boat to the data center :)). Equipment must be protected properly, but clients must have physical access to the premises as well (have in mind that unlike Google, we have clients with their own hardware and thus they need access). Size also matters. Lowering energy consumption is much easier for smaller data rooms located within a SME, than a large data center.

One of the easiest ways of saving energy is raising the airflow temperature. In the past it was almost mandatory to have an inflow temperature of 21degrees, however server equipment can operate at higher temperatures. We currently use an average temperature of 24 degrees and might increase temperature in the future. To be able to raise temperature, you will probably also need to make sure no short circuiting of hot and cold air is possible (see also ‘Cooling a data center’). Nowadays you will see concepts like the Cold-Corridors being used more and more. Various options can be taken even with legacy data centers (closing empty racks with covering panels, using efficient Uninterruptable Power Supply (like Delta Conversion from APC)).

Not every technology can be used in all situations. As said before, building a data center in the sea or coal mine is no option for multiple client data centers, but might be an option for compagnies like Google, MicroSoft etc. Using free-cooling (ambient temperature is used for chilling water) can be used in cold countries, but is not an option for example Dubai.

New techniques will become available the next years. What can be used is depending on several business parameters. There is not a ‘one-suits-them-all’ solution. Saving energy remains a pioneering journey for many.

Co-author: Laurens Rosenthal, Innovation Director EvoSwitch Datacenter Netherlands

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