Reducing power consumption for server-class computers is important, since increased energy usage causes more heat dissipation, greater cooling requirements, reduced computational density, and higher operating costs. For a typical data center, storage accounts for 27% of energy consumption. Conventional server-class RAIDs cannot easily reduce power because loads are balanced to use all disks, even for light loads.

We have built the power-aware RAID (PARAID), which reduces energy use of commodity server class disks without specialized hardware. PARAID uses a skewed striping pattern to adapt to the system load by varying the number of powered disks. By spinning disks down during light loads, PARAID can reduce power consumption, while still meeting performance demands, by matching the number of powered disks to the system load. Reliability is achieved by limiting disk power cycles and using different RAID encoding schemes. Based on our five-disk prototype, PARAID uses up to 34% less power than conventional RAIDs while achieving similar performance and reliability.

Bio

Andy Wang received his Ph.D. and M.S. in computer science from UCLA in 2003 and 1998, and his B.S. from UC Berkeley in 1995. He joined the Department of Computer Science at Florida State University as an Assistant Professor in 2003. His research interests include file systems, optimistic peer replication, performance evaluation, ad hoc network routing, operating systems, and distributed systems. More information on his work is available at http://www.cs.fsu.edu/~awang/