17.op/JKO.shirriff
.m From shirriff@allspice.Berkeley.EDU Mon Aug 30 18:43:24 1993
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High-Performance RAID File Systems

Ken Shirriff

(Professor J. K. Ousterhout)

A disk array such as RAID-II poses new challenges for file systems.
RAID-II consists of a high-bandwidth disk array connected to a
high-bandwidth network via a specialized controller board with a large
RAM cache. Unlike normal disk systems, the datapath does not go
through the file server CPU. This prevents the file server from
becoming a bottleneck, but requires redesign of the file system. A
RAID-II file system must use the new datapath, manage cached data in
controller memory, and handle very high data rates.

My research investigates methods of providing the high bandwidth of
RAID while providing traditional file system operations and
abstractions. The key features of my file system are that it uses LFS
(log-structured file system) to increase write bandwidth, it has a
high-bandwidth path that keeps data out of the file server, and it uses
parallelism to keep latency from wasting the potential bandwidth. I am
examining ways of efficiently using a separate controller memory cache
and file server memory cache while maintaining consistency. I am also
exploring ways of maximizing the RAID performance through pre-fetching.