RAID-II: A Scalable Storage Architecture for

High-Bandwidth Network File Service

Edward K. Lee Peter M. Chen John H. Hartman
Ann L. Chervenak Drapeau Ethan L. Miller Randy H. Katz
Garth A. Gibson David A. Patterson

Abstract

RAID-II (RAID the second) is a scalable high-bandwidth network file server for heterogeneous computing environments characterized by a mixture of high-bandwidth scientific, engineering and multi-media applications and low-latency high-transaction-rate UNIX applications. RAID-II is motivated by three observations: applications are becoming more bandwidth intensive, the I/O bandwidth of workstations is decreasing with respect to MIPS, and recent technological developments in high-performance networks and secondary storage systems make it economical to build high-bandwidth network storage systems.

Unlike most existing file servers that use a bus as a system backplane, RAID-II achieves scalability by treating the network as the system backplane. RAID-II is notable because it physically separates files service, the management of file metadata, from storage service, the storage and transfer of file data; stripes files over multiple storage servers for improved performance and reliability; provides separate mechanisms for high-bandwidth and low-latency I/O requests; implements a RAID level 5 storage system; and runs LFS, the Log-Structured File System, which is specifically designed to support high-bandwidth I/O and RAID level 5 storage systems.

Key words: high-bandwidth network file service, network storage, mass storage system, RAID.