A File Level RAID in Blue Whale File System

Blue Whale File System (BWFS) is a distributed file system with proven high performance and high scalability. In order to provide high reliability for BWFS, we designed and implemented a new architecture named BW-FILERAID, which combines distributed file system well with the RAID technology. BW-FILERAID uses client-driven file-level RAID to satisfy the requirement of reliability and optimizes the RAID performance by utilizing the file system information. The schemes of Dynamic Stripe Allocation (DSA) and Asynchronous Parity Calculating (APC) are proposed to reduce the impact of small write performance problem which is incurred by classic RAID5 implementation. This paper introduces and evaluates BW-FILERAID. As compared with the Linux software RAID5 systems, BW-FILERAID can achieve significantly higher WRITE performance which increases by 8.2~25.9% while with the same READ performance as RAID0. At last, BW-FILERAID also has very good system scalability.