Design issues on request migration for video-on-demand services

A random early migration (REM) algorithm is proposed to handle the request migration in a video-on-demand (VoD) server system. When a new request is dispatched to a media server, REM compares the current service load with thresholds and decides whether request migration is needed with a certain probability, which is a function of the service load. To facilitate the performance analysis of REM, we introduce a state matrix structure to record the current system load status. Based on the state matrix structure, we develop a state transition method to study the parameter effect on the REM performance and compare the real time performance between REM and traditional migration with early start (TMES). The simulation result shows that, in terms of the migration cost, REM can achieve a more enhanced performance than the traditional migration scheme. Compared to TMES, REM introduces smoother migrations between media servers and thus leads to a lower real-time system load.