Ripple-RAID: A high-performance and energy-efficient raid for continuous data storage

The applications, such as video surveillance, backup and archiving, have inherent workload characteristic and I/O access pattern, and require specialized optimization for storage energy saving. Partial parallelism in RAID is beneficial to storage energy saving, but generally makes RAID perform small writes, which heavily deteriorates the performance. A high-performance and energy-efficient RAID, Ripple-RAID, is proposed for these applications. A new partial-parallel data layout is presented, and by comprehensively employing strategies such as address mapping, out-place update, generating parity data progressively based on pipeline, and segmented data recovery, Ripple-RAID not only obtains energy efficiency of partial parallelism but also eliminates the small writes incurred by partial parallelism while providing single disk fault tolerance. When write workload is 80% sequential and transfer request size is 512KB, the write performance of Ripple-RAID is 3.9 times that of S-RAID 5, 1.9 times that of Hibernator and MAID, and 0.49 times that of PARAID and eRAID 5; meanwhile its energy consumption is 20% less than S-RAID 5, 33% less than Hibernator and MAID, 70% less than eRAID 5, and 72% less than PARAID.