Adaptive load balancing in disk arrays

Abstract

Large arrays of small disks are providing an attractive approach for high performance I/O systems. In order to make effective use of disk arrays and other multi-disk architectures, it is necessary to develop intelligent software tools that allow automatic tuning of the disk axrays to varying workloads. In this paper we describe an adaptive method for data allocation mad load balancing in disk axrays. Our method deals with dynamically changing access frequencies of files by reallocating file extents, thus "cooling down " hot disks. In addition, the method takes into account the fact that some files may exhibit periodical access patterns, and considers explicitly the cost of performing the “cooling” operations. Preliminary performance studies based on real-life I/O traces demonstrate the effectivity of this approach.