Paraid

The rising cost of energy is becoming a concern beyond mobile computing platforms. Server-class computers cannot simply consume more power, since increased energy consumption translates into more heat dissipations, more cooling requirements, reduced computational density, and higher operating costs. For a typical data center, storage alone accounts for 27% of the energy consumption, making storage an important target for energy reduction. Unfortunately, conventional server-class RAIDs are not designed for saving power, because loads are balanced in such a fashion that they require the use of all disks in the array for even light system loads. This work introduces the Gear-Shifting Power-Aware RAID (PARAID), which reduces energy in server-class computing while retaining performance and reliability. The design of PARAID uses a skewed striping pattern to adapt to the system load by varying the number of powered disks. By powering off disks during periods of light load, PARAID can reduce the power consumed by a comparable conventional RAID device by 23%. By matching the number of powered disks to the system load, PARAID can also demonstrate request completion time and latency comparable to conventional RAID.