Chapter 1 MANAGING PARALLEL DISKS FOR CONTINUOUS MEDIA DATA Edward Chang University of California, Santa Barbara echang@ece.ucsb.edu Chen Li and Hector Garcia-Molina Stanford University chenli@stanford.edu,hector@db.stanford.edu Abstract In this study we present a scheme called two-dimensional BubbleUp (2DB) to manage parallel disks for continuous media data. Its goal is to reduce initial latency for interactive multimedia applications, while balancing disk loads to maintain high throughput. The 2DB scheme consists of a data placement and a request scheduling policy. The data placement policy replicates frequently accessed data and places them cyclically throughout the disks. The request scheduling policy attempts to maintain free “service slots” in the immediate future. These slots can then be used to quickly service newly arrived requests and fast-scan requests. Through examples and simulation, we show that our scheme significantly reduces initial latency and maintains throughput comparable to that of the traditional schemes. Keywords: multimedia, data replication, initial latency, disk array. 1. INTRODUCTION Media servers are designed to provide large numbers of presentations in the form of audios, movies, or news clips. These servers need a large number of disks, not only for storing the data, but also for providing the required high bandwidth for all simultaneous streams. In this paper we propose a scheme called two-dimensional BubbleUp (2DB) that manages parallel disks for large media servers. The objective of 2DB is to minimize initial latency while maintaining high throughput. We define initial latency as the time between the request’s arrival 1