Performance evaluation of distributed iSCSI RAID

Abstract

iSCSI is a newly emerging protocol with the goal of implementing the storage area network (SAN) technology over TCP/IP, which brings economy and convenience whereas it also raises performance and reliability issues. This paper identifies the performance bottleneck of iSCSI, and then proposes a distributed iSCSI RAID to improve the performance by stripping data among iSCSI targets (S-iRAID) and improve the reliability by using rotated parity for data blocks (P-iRAID). Numerical results using popular benchmark have shown dramatic performance gain. S-iRAID improves the average throughput from 11.7MB/s to 46.1 MB/s by striping data among only three iSCSI targets. S-iRAID and P-iRAID can speed up the iSCSI performance by a factor of up to 6.6 and 2.17, respectively.