Track-Pairing: A Novel Data Layout for VOD Servers with Multi-Zone-Recording Disks

Multi-zone recording increases disk capacity b y approximating fixed linear recording density. With $xed rotation speed, however, transfer rate varies with track location, as does the number of video streams that can be played concurrently. This paper proposes TrackPairing, a deterministic scheme for static intra-disk data layout. By recording each movie alternately on “outer” tracks and their “inner” counterparts, a disk’s throughpui becomes independent of the viewers’ choices and its guaranteed streaming capacity is maximized. With a 1.8:l ratio of outermost t o innermost track capacities, guaranteed streaming capacity is increased b y 40 percent, and as merely 22 percent below the streaming capacity of the outermost track! Temporal overhead is modest, and required buffer sizes are smaller than those with the Logical Tracks scheme, which also maximizes guaranteed throughput. TrackPairing has been implemented under Microsoft’s Windows N T , and can be extended t o multiple disk drives.