Source : Free On-Line Dictionary of Computing

Scan-EDF
     
         A variation of the {Scan} disk aceess
        algorithm for use in a {real-time} environment where, in
        general, requests are served according to {Earliest Deadline
        First}.  If two requests share the same deadline, they may be
        reorganised according to Scan.
     
        A typical example is a video server that retrieves video data
        from a hard disk.  The playback of a video impose tight
        real-time constraints but if the server retrieves data once
        every second for each video channel, Scan-EDF can be applied,
        reducing the {seek} {overhead}.
     
        (1995-11-15)