The generator is apparently a late addition to the scheme – in October 2010 Aubé told IT journal ITespresso that the data centre wouldn’t include a generator because its high-availability needs were met with the existing power infrastructure. The 99.995 percent availability rate is supported by supports backup features such as hot-swappable hardware and redundant computing infrastructure and electrical circuits. The redundant systems mean components can be replaced on the fly, so that maintenance can be carried out with no downtime. Fresh-air cooling
Marilyn has a PUE efficiency rating of 1.3, meaning 2.31 MW out of 3 MW will be directly usable by the IT equipment. That’s in line with other “green” data centres, such as a Hemel Hempstead facility opened by Gyron in July, which claimed a PUE of between 1.2 and 1.3. The industry average PUE is 2.5, according to Gyron. For power backup, the data centre uses an unusual feature – two flywheel-powered UPS systems, which take over in the event of a power failure until the generator comes online. These UPS systems, which have only become feasible for data centres in recent years, allow Marilyn to dispense with lead batteries. Marilyn is scheduled to open for business on 26 September. A study published in August found that data centre power use has grown significantly less than predicted over the past few years, largely due to the 2008 economic crisis. The study, carried out by a consulting professor at Stanford University, found that electricity used by data centres worldwide increased by about 56 percent from 2005 to 2010. This might seem a big increase, but experts had predicted energy use would double over this period. In the US data centre electricity use grew by about 36 percent, according to Koomey’s figures. This report is translated and extended from an article by Rénald Boulestin, Silicon France. Editing by Peter Judge and Matthe Broersma.