areal density throughout, then when read or written in CAV mode, the data rate is higher for the outer tracks than for the inner tracks (because for the same rotation on the inner track, more distance is travelled on the outer track), whereas in CLV mode, the data rate is the same everywhere.

An advantage of CAV mode over CLV is that the drive mechanism is easier to engineer (and less expensive to build). Another advantage is that a device can switch from reading one part of a disk to reading another part more quickly, because in CLV