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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


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.