EMC for example, has seen a surge in interest for 500GB disc drives in its Symmetrix DMX platforms, according to Bob Wambach, director of EMC Symmetrix product marketing. The reason? A 500GB drive offers 66% more capacity than a 300GB version but consumes the same power in the same space footprint, he said.
The problem is especially pronounced in urban areas like New York City, Wambach said. In some cases, customers tell him, "I can't physically get more power into my datacentre, but I still need to do more."
Indirectly, data growth and users' desires for disc-based data protection are inspiring more power-efficient storage designs.
"Our design goal was to put 1,000 disc drives in a single box," said Chris Santilli, chief architect and co-founder at Copan Systems. Copan's product uses a massive array of idle disks (MAID) architecture, which only powers on up to 25% of the drives at a time to improve power utilisation and extend the life of the disc drives.
The result, the Revolution array, fell short of the 1,000 drive goal - but at 896 drives, it's still approximately four times denser than an average array and uses only one quarter the power, Santilli said. Given that, "we feature 16 times better power per disc than other systems," he added. The Revolution is used as a virtual tape library (VTL) and archiving platform.
But mechanical improvements to storage arrays can only improve power consumption so much, said David Scott, president and CEO at 3Par Data. At some point, storage managers need to address the most egregious source of waste - poor utilisation.
"Data storage systems are probably the most energy-inefficient systems out there," Scott said. "Average disk utilisation rates continue to hang around the 20% to 25% level. More than half of the disc drives sitting there are effectively wasted," he added.
3Par's answer to storage power inefficiency is thin provisioning, its oversubscription feature that assigns disc capacity to an application only when it's actually needed, reducing the number of disc drives required in the system.Warren Habib, chief technology officer at Fotolog, an online content sharing company in New York and a 3Par customer, corroborated Scott's claim. With thin provisioning, Fotolog uses 200 fewer disc drives in its system than it would without. Assuming 0.65 kWh to power and cool a drive, "with 8,760 hours in a year, we would be using 200 x .065 x 8760 = 113,800 additional kilowatt hours," Habib said. At a hypothetical cost of $.08 kWh, "we save $9,110 year and, more importantly, save that much wear and tear on the environment," he noted.