I've been sent this information by 3PAR. "Customers using 3PAR Utility Storage and Thin Provisioning can purchase one-half to one-third as many disk drives as they would have done otherwise."

"To date, 3PAR has sold 12 petabytes of capacity yet our customers have provisioned around 30 petabytes total. This represents an annualised energy savings of $4.4M for 3PAR customers. In energy terms, crude oil savings by 3PAR customers are estimated to amount to 80,000 barrels of oil equivalent -- enough oil to fuel more than 3,300 cars for a full year! In environmental terms, the carbon emissions saved by 3PAR customers are approximately 35,300 tons of CO2, the equivalent emissions of more than 6,000 cars for an entire year. "

"On a global basis, assuming an installed based of 108 million enterprise disk drives, the energy cost savings would amount to greater than $3.6 billion if all disk systems would have been sold with Thin Provisioning. In energy and environmental terms, the savings would amount to 1.3 billion gallons of gasoline and nearly 30 million tons of CO2 emissions."

I wonder if data centre carbon footprints are going to have to be monitored. Maybe some keen US senators will promote a Carbox measure forcing businesses to provide carbon footprint numbers in their annual reports. Certainly it is beginning to as if electricity consumption by data centres is moving to what Cisco might call 'top of mind'.

It is also beginning to be the case that we'll get a raft of 'my storage product is greener than yours' claims. So far I reckon five things actually work in decreasing disk-based storage energy costs: virtualisation; thin provisioning; MAID; de-duplication; and archiving to off-line tape/optical storage.

If today's yesterday's release of the Stern Report helps cause a sea-change in thinking about energy consumption then these four technologies are going to become more and more important.