Flash-Aware RAID Techniques for Dependable and

Flash-Aware RAID Techniques for Dependable and

High-Performance Flash Memory SSD

◈  연  사 : 신 동 군 교수 (성균관대학교 정보통신공학부)

◈ 일  시 : 2010년 4월 16일 (금) 오후 2:45 ~ 4:15

◈ 장  소 : LG동 강당

◈ 초청자 : 유 승 주 교수 (T.2379)

Abstract

Solid-state disks (SSDs), which are composed of multiple NAND flash chips, are replacing hard disk drives (HDDs) in the mass storage market. The performances of SSDs are increasing due to the exploitation of parallel I/O architectures. However, reliability remains as a critical issue when designing a large-scale flash storage. For both high performance and reliability, Redundant Arrays of Inexpensive Disks (RAID) storage architecture is essential to flash memory SSD. However, the parity handling overhead for reliable storage is significant. We propose a novel RAID technique for flash memory SSD for reducing the parity updating cost. To reduce the number of write operations for the parity updates, the proposed scheme delays the parity update which must accompany each data write in the original RAID technique. In addition, by exploiting the characteristics of flash memory, the proposed scheme uses the partial parity technique to reduce the number of read operations required to calculate a parity. We evaluated the performance improvements using a RAID-5 SSD simulator. The proposed techniques improved the performance of the RAID-5 SSD 46% and 37% on average in comparison to the original RAID-5 technique and the previous delayed parity updating technique, respectively.