Using Multiple Round Lengths to Support Heterogeneous Streams on Continuous Media Servers

On continuous media(CM) servers, data are handled periodically. The length of the period or round length has a strong innuence on the performance of CM servers, and the optimal round length for a server is determined mainly by the bit rate of the media object. As far as we know, all existing disk scheduling schemes are of single round length, in which all objects are serviced using a same round length regardless of their bit rates. Consequently in case of heterogeneous media servers, which services high bit-rated objects and low bit-rated objects simultaneously, they could not service streams using their respective optimal round length. In this paper, a model of CM server which services each object using its optimal round length is presented for the rst time. The performances of the single round length model and the multiple round length model are compared through extensive simulation and the multiple round length scheme always shows equal or better performance.