Partial Parity Cache and Data Cache Management Method to Improve the Performance of an SSD-Based RAID

In this paper, a partial parity cache and data cache management method is presented for reducing the parity updating cost of a solid-state disk (SSD) based redundant array of inexpensive disk (RAID) system, thereby which the input/output (I/O) performance of the RAID system can be improved. SSDs have many advantages compared to hard disk drives. However, it is not advisable to directly add SSDs into a RAID system because doing so will decrease the performance and the life-time of the SSDs. In the RAID-5 system, parity generation includes read and write operations to the SSDs. Whenever there is a new write request to the RAID, the related parity must be updated and written to the SSDs. Such frequent parity updates result in poor RAID performance and shortens the life-time of the SSDs. This paper combines the prior methods and the proposed efficient buffer management method with a data cache. The proposed method reduces the number of read and write operations for generating parities in the RAID system. Experimental results show that the I/O performance of the RAID-5 system can be improved by 76% by using the proposed method.