sectors and addressing was by track and sectors.
*Blocks were variable length, and blocks were addressed by track and record number.
*Blocks were variable length with a key, and could be searched by key content.Some devices were divided into logical cylinders, and addressing by track was actually logical cylinder and track.

The performance of a drum with one head per track is comparable to that of a disk with one head per track and is determined almost entirely by the rotational latency, whereas in an HDD with moving heads its