The present invention provides methods and systems for storage of data. In one aspect, the invention provides a data storage system that includes a plurality of storage devices, such as, disks, for storing data, and a controller that implements a policy for managing distribution of power to the storage devices, which are normally in a power-off mode. In particular, the controller can effect transition of a storage device from a power-off mode to a power-on mode upon receipt of a request for reading data from or writing data to that storage device. The controller further effects transition of a storage device from a power-on mode to a power-off mode if no read/write request is pending for that storage device and a selected time period, e.g., a few minutes, has elapsed since the last read/write request for that storage device.
FEDERALLY SPONSORED RESEARCH
 This invention was made with government support awarded by Department of Energy under Contract Number DE-FG03-01ER83315. The government has certain rights in the invention.