A probabilistic multi-cycle model for serving continuous streams from disks

Existing models for serving continuous streams from disks are generally based on worst-case deterministic head displacement times and on a round-robin strand service approach consisting of serving all strands once per round. We propose an alternative approach, where the head displacement time is described as a random variable with known probability density and where strands are served in a round-robin manner consecutively several times per service period. By establishing the frame loss rate separately in each cycle and for each of the strand´s display deadlines, we compute the mean number of lost frames per second for a given configuration. By serving strands consecutively several times in consecutive cycles, we show that for a given frame loss rate, less buffer space is needed than in the conventional single round approach