constant linear velocity

(CLV) A way of controlling the rotation of the disks in a disk drive in which the linear velocity of the disk surface relative to the read/write heads is kept constant.

In order to achieve constant linear velocity, the disk must rotate faster (at a higher angular velocity) when reading or writing tracks closer to the centre.

Having a constant linear read/write speed along the track means that the electrical signal to and from the heads has a constant data rate (bits per second), thus simplifying the timing of the drive electronics somewhat. However, rotating at less than the maximum possible rate sacrifices some potential performance compared to the alternative, constant angular velocity. Also, varying the rate causes more vibration and consumes more energy.