The applications

such as video surveillance

backup

and archiving

generate massive storage data

which make the energy consumption of storage devices increase rapidly. S-RAID can reduce the storage energy consumption of above applications significantly. In order to make more disks standby for energy saving

S-RAID prefers to small write. However

performing small write requires additional and equal amount of read operations for generating parity data

and the write performance of S-RAID is decreased. The existing prefetching mechanism mainly implements at the file system level

and cannot sense the read operations generated by small write at RAID level

such as reading old data and reading old parity. So it can not prefetch these old data and old parity data. Therefore

a RAID-level prefetching algorithm for small write of S-RAID is proposed

which is triggered by small write operations and performs at RAID level. It asynchronously prefetches the old data and old parity data required by small writes in large granularity according to the data layout of S-RAID. The write performance of S-RAID can be improved by about 40% without any additional hardware cost.