Tuesday, May 01, 2007

Green IT

I've been digging more and more into the issue of sustainability and the responsibility of the Data Centre for energy consumption. In the UK this is estimated at around 1.5% of gross domestic consumption, which seems a lot to me. However, when you consider the average utilisation of servers running around 15-20% (which is probably optimistic) its actually laden with a fair amount of wastage. Assuming that consumption is linear in nature - which it is probably not. When you consider that powering a box takes about twice as much power as cooling it the statistic gets worse. If you then consider that older boxes may be idle and yet running at 85% consumption, it gets worse still. At least newer processors use only around 25% in idle state and can now be switched off altogether and remotely powered up and operational in less than 15 minutes. This is a story which will run and run, because I know that the IT Directors and Data Centre managers out there are quite passionate about power. Its now consuming up to 40% of their budget and, we can see from the above, to little good effect. Its something we need to get to grips with. How?
Well, using virtualisation allows server power to be maximised in a fewer, more efficient boxes for end users; server virtualisation allows older, more expensive, boxes to be replaced by newer more efficient servers - and the Xen hypervisory looks good at the price for only single digit overhead against double digit performance improvement.
There's some smart ideas around from HP on power management in the data centre, combined with grid middleware and system management workloads can be distributed across the network and usage levels optimised to your choice. And while we're there, are you sure you need to own your own infrastructure? There's always the opportunity to leverage someone else's investment in carbon neutral infrastructure for hosting some of your applications or to provide extra capacity for business continuity.
Multi-core processors seems to prosper best in virtualised environments, at least that's one way of running application tasks in parallel, simply replicate them. Works well if transactions are self contained. A little more challenging if not. But there are ways of clustering which will work for more traditional data base configurations, see Oracle 10G. Course, it would be good if we could dust off those old parallel programming skills and redesign applications for these environments. See the BCS Parallel Processing Specialist Group for some folk who understand this question!!
Finally, its such a shame that we have so much AC:DC conversion lying around, Google, amongst others, have suggested a minimum standard of 80% efficiency for all such exercises. Does this cost you much? Well a recent experiment successfully ran a data centre on DC power only, just one conversion, at a saving of 20% of energy consumed! Run the maths, there's plenty of opportunity here to start reducing that power bill.



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