I find it ironic that Seagate chose Earth Day to celebrate the shipment of its billionth disk drive. After all, increased drive dependency in the datacenter is fast transforming into an unsustainable energy demand.

Of course, the blame does not fall entirely on drive vendors. For the most part, they are simply responding to opportunity. But this Earth Day billionth-drive milestone can't help but remind me of oil companies feasting on record profits while consumers struggle with high prices at the pump.

Think I'm exaggerating the environmental impact of the electricity used in the datacenter? Consider this: According to an EPA study on datacenter energy use, servers and other computer room equipment burned 61 billion kilowatt-hours in 2006 -- about 1.5 per cent of all electricity used in the US.

And, if we do nothing, energy use in the datacenter will more than double by 2011, creating an energy demand equivalent to 10 additional power plants, according to the report.

More disheartening is that the report -- the most comprehensive analysis of power usage in IT that I have read -- is likely optimistic in terms of its estimates. After all, storage demand could very well grow at a faster pace than anticipated, sapping even greater levels of energy in the process.

According to that EPA report, storage accounted for only 5 per cent of the energy devoured by the datacenter in 2006, with servers and infrastructure absorbing 90 per cent. Yet whereas virtualization and other consolidating techniques provide quick, easy efficiencies for servers, storage consolidation is a more difficult undertaking, and one that may not, in fact, generate an equivalent payoff in efficiency.

Yes, larger capacity drives could, for example, cut the number of spindles allocated to an application down to 10 per cent or less. Yet that benefit could very well be nullified by increased demands elsewhere -- increased reliance on disk-to-disk backups, increased amounts of reference data stored in online repositories, both of which translate into more spinning drives.

I agree with the point that Kelly Lipp, vice president of manufacturing and CTO of STORServer makes in his blog "How Green is My Backup", which is, in essence, that storing data on tape puts a much lighter demand on energy than using disk drives. However, I can't agree with his conclusion that going back to tape for the majority of the data and leaving only what needs frequent and fast access on disk is the way to go, in the main because identifying the latter is not always possible.