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Tutorials Program - SIGMETRICS 2001 / Performance 2001

Performance and Modeling Issues in Disk Array Systems

Eitan Bachmat <>

Performance Consultant
EMC Corporation
Hopkinton, Massachusetts

Affiliation: Lecturer at Ben-Gurion U. Beer-Sheva Israel <>

Disk arrays and other mass storage devices differ from most computer systems in their incorporation of mechanical elements, namely disks or tapes or in the future MEMS based storage devices. We will concentrate our attention on disk based mass storage devices, namely disk arrays. We shall explore some of the research aimed at minimizing the amount of mechanical movement involved in servicing user requests. A second theme which is central to the discussion of disk array performance is parallelism, since disk arrays contain many devices, again disks, which can act in parallel.

Trying to optimize a disk array's performance along one of these themes may hurt the other. In many cases though these goals are positively correlated.

The main techniques we will describe are : Caching, choice of data layout the use of mirroring and disk queueing.

We will also briefly discuss basic models for the host request stream since such models are essential for producing any results.

Who should attend?
Anyone interested in modeling or analyzing the performance of single or multiple disk systems. Another intended group is people who like to see math applied to real life situations.

The material is self contained, all the notions which are required to state the results will be explained. In particular no previous familiarity with disk arrays is needed.

The speaker received his BA and MA degrees in mathematics from the Hebrew U. in Jerusalem and his Ph.D in math from M.I.T. He currently teaches at Ben Gurion U. in Israel and conducts research on disk arrays. In addition he has served for the last several years as a performance consultant to EMC Corp., in this capacity he has worked on performance algorithms related to the symmetrix disk array family.

[Last updated Wed Jan 3 2001]