Track-pairing: a novel data layout for VOD servers with multi-zone-recording disks

Multi-zone recording increases disk capacity by approximating fixed linear recording density. With fixed rotation speed, however, transfer rate varies with track location, as does the number of video streams that can be played concurrently. This paper proposes Track Pairing, a deterministic scheme for static intra-disk data layout. By recording each movie alternately on "outer" tracks and their "inner" counterparts, a disk's throughput becomes independent of the viewers' choices and its guaranteed streaming capacity is maximized. With a 1.8:1 ratio of outermost to innermost track capacities, guaranteed streaming capacity is increased by 40 percent, and is 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 Track scheme, which also maximizes guaranteed throughout. Track-Pairing has been implemented under Microsoft's Windows NT, and can be extended to multiple disk drives.