Analyzing the Performance of Asynchronous Disk Arrays for Multimedia Retrieval

Due to the periodic nature of media playback, a multimedia server can service multiple clients simultaneously by proceeding in rounds, retrieving a fixed number of media units (e.g., video frames) for each client during each round. In this paper, we analyze the performance of a conservative and an aggressive policy for retrieving media units from an asynchronous disk array. In the conservative servicing policy, a server completely retrieves all the required media units during a round prior to initiating the next round. A server employing the aggressive servicing policy, on the other hand, requires the disks to synchronize only over a finite sequence of rounds. We have carried out extensive simulations to measure the effectiveness of the conservative and the aggressive servicing policies on the utilization of asynchronous disk arrays. We present and analyze our simulation results.