S-RAID 5:An Energy-Saving RAID for Sequential Access Based Applications

In modern-day storage systems,disk arrays and their cooling systems consume a major portion of total system power consumption.The existing research work on energy conservation mainly concentrates on optimizing the storage systems for random access-based applications.However,for the widely-used storage systems for sequential access-based applications,such as video surveillance,continuous data protection(CDP),virtual tape library(VTL),few schemes are proposed to gain better energy conservation according to their inherent characteristics with I/O performance guarantee so far.To this end,S-RAID 5,an energy-saving RAID system,is proposed for sequential access-based applications.In S-RAID 5,a local-parallelism strategy is employed: the entire storage area of the array is partitioned into different groups,and in each group a parallel data access scheme is adopted.Data grouping makes it possible to keep only a portion of disks active while keeping the rest standby.On the other hand,the intra-group parallelism is used to provide the performance guarantee.With an appropriate caching strategy to filter out a small amount of random accesses,S-RAID 5 can achieve prominent energy saving.In a simulation experiment of 32-channel video surveillance with D1 resolution standard,the measurement results of 24-hour power consumption show that the power consumption of S-RAID 5 is 59%,23%,21%,and 21% of those of Hibernator,eRAID,PARAID,and GRAID,respectively,while meeting the I/O performance and single-disk fault tolerance.