IDA-based Redundant Arrays of Inexpensive Disks

Parallel disks can improve I O performance in a man ner analogous to the use of parallel processors to im prove computation times However due to their data storage function reliability issues become exceedingly important Currently proposed schemes use shadow ing or parity to achieve reliability in parallel disks In this paper we introduce the idea of using the Informa tion Dispersal Algorithm IDA of Michael O Rabin to distribute data and redundancy information uni formly among multiple disks and compare the perfor mance and reliability characteristics of shadowing par ity and IDA We discuss some ways to take advantage of the uniformity of data placement and argue that IDA is the algorithm of choice for achieving reliability and performance in parallel disk systems