This article can also be found in the Premium Editorial Download "Storage magazine: Using file virtualization to improve network-attached storage."
Download it now to read this article plus other related content.
The cheapest option is to increase storage utilization. "You want to increase the utilization of the spinning motors and platters that you already have," says Jonathan Eunice, founder and principal IT advisor at Illuminata Inc., Nashua, NH. Once the drive is spinning, additional utilization essentially costs nothing from an energy standpoint.
Erie 1 Board of Cooperative Education Services (BOCES) is a longtime mainframe shop in West Seneca, NY, that provides applications and IT services to more than 100 public school districts in western New York. Chief information officer Carol Troskosky has moved the organization to new mainframes with the latest channel-attached storage. (Channel-attached describes the high-speed, direct interconnect between the mainframe and shared peripherals; in this case, shared IBM storage arrays.) She then boosted utilization by consolidating open systems using Linux on the mainframe, while capitalizing on the increased energy efficiency of big iron. Erie 1 BOCES has also joined with other agencies in New York to buy energy cooperatively. But Troskosky still expects energy consumption to increase. "We try to keep our energy costs as low as possible," she says, but the organization must still meet increased demand for its services.
Beyond consolidation, storage managers can deploy storage in more energy-efficient ways. If you don't need high performance, deploy 7,200 rpm or 10,000 rpm disks rather than 15,000 rpm models, as the slower speeds use less energy. Similarly, smaller form-factor (2.5-inch) disk drives require only 5 volts vs. 12 volts for standard 3.5-inch form-factor drives. Small form factors, however, usually have smaller capacity (see "Energy tradeoffs," this page).
Direct current (DC) can also be an energy-saving alternative. According to IDC, DC-powered equipment allows a portion of the heat load to move from the servers to the rectifiers, reducing heat at the system level by 20% to 40% vs. a traditional alternating current (AC)-powered rack. "DC offers some efficiency, but you're mainly moving the problem someplace else," says TheInfoPro's Gill.
This was first published in March 2007