Evaluation of disk-retry methods for continuous media data

Conventionally, hard disks had been used mainly to store programs or data to be used for calculations. However, as the disk capacities and transfer speeds increased, hard disks began to be used in a wider variety of ways including the storage and playing of continuous media data such as movies or music. When an error occurs while reading a hard disk, a retry is executed. However, this causes an extremely long delay. Although for computational data, the delay should be ignored and the maximum number of retries should be executed to guarantee reliability, when playing continuous media, an increase in continuity may be demanded even if the data reliability decreases. Therefore, in this paper, the authors consider methods of dynamically controlling the number of retries to increase the data reliability as much as possible while maintaining continuity. First, they investigate single disk‐retry techniques. Then, they assume a disk array configuration and propose a technique that combines dynamic retry count control and RAID5 parity calculations. Also, to verify the effectiveness of the proposed technique, they propose several evaluation indices and perform simulations to evaluate the single disk‐retry techniques and retry techniques that include switching between retries and parity calculations for a disk array. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 37(1): 47–60, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20333