Online algorithms for prefetching and caching on parallel disks

Parallel disks provide a cost effective way of speeding up I/Os in applications that work with large amounts of data. The main challenge is to achieve as much parallelism as possible, using prefetching to avoid bottlenecks in disk access. Efficient algorithms have been developed for some particular patterns of accessing the disk blocks. In this paper, we consider general request sequences. When the request sequence consists of unique block requests, the problem is called prefetching and is a well-solved problem for arbitrary request sequences. When the reference sequence can have repeated references to the same block, we need to devise an effective caching policy as well. While optimum offline algorithms have been recently designed for the problem, in the online case, no effective algorithm was previously known. Our main contribution is a deterministic online algorithm threshold-LRU which achieves O((MD/L)2/3 ) competitive ratio and a randomized online algorithm threshold-MARK whic...

• Type: Conference
• Year: 2004
• Where: SPAA
• Authors: Rahul Shah, Peter J. Varman, Jeffrey Scott Vitter
• Keywords: Competitive Ratio, Distributed And Parallel Computing, Parallel Disk, Request Sequence, SPAA 2004