Asynchronous disk interleaving: approximating access delays

Abstract

The performance implications of asynchronous disk interleaving are examined. In an asynchronous system, adjacent subblocks are placed independently of each other. Since each of the disks in such a system is treated independently while being accessed as a group, the access delay of a request for a data block in an n-disk system is the maximum of n access delays. Using approximate analysis, a simple expression for the expected value of such a maximum delay is obtained. The analysis approximation is verified by simulation using trace data; the relative error is found to be at most 6%.