Quasi-constant linear-velocity disk having corresponding radii of adjacent annular zones related by a rational number for distributing prerecorded indicia to form a coherent write clock signal

A disk (magnetic, magneto-optical or optical) includes information-bearing tracks having prerecorded indicia, preferably tracking pads, distributed uniformly along each track for phase locking a write clock so as to write user data subsequently between the tracking pads, in the presence of random fluctuations in disk speed. The tracks are grouped into a plurality of annular zones encircling the center of the disk, wherein the ratio of the inner radius (or outer radius) of a given zone to the corresponding radius of the adjacent inner zone is a rational number, n/d, which is the same for each adjacent pair of zones. Each track within a given zone, i, has a fixed number of radially aligned tracking pads, Pi, calculated from: Pi=(n/d)i-1x(d)N-1 where i is 1 for the innermost zone and is N for the outermost zone.