Next you have to calculate the number of tracks available on each cylinder for prime data records. You cannot include tracks set aside for cylinder overflow records.

Prime data tracks = Tracks per cylinder - Overflow tracks per cylinder
per cylinder        - Index tracks per cylinder

Example: If you set aside 5 cylinder overflow tracks, and you need 0.385ths of a track for the track index, 9.615 tracks are available on each cylinder for prime data records.

Prime data tracks per cylinder  = 15 - 5 - (0.385) = 9.615