A magnetic disk drive having a reduction in repeatable runout (RRO) effects is
disclosed. The disk drive has a head disk assembly (HDA) and a sampled servo controller.
The HDA includes a rotating magnetic disk, an actuator, and a transducer head.
The magnetic disk has a plurality of embedded servo sectors for storing servo information
including repeatable runout (RRO) cancellation values and RRO cancellation value
error correction code (ECC) data at a servo data rate. The RRO cancellation value
ECC data is only for detecting and correcting errors in the RRO cancellation values.
In between the embedded servo sectors are data sectors for storing user data at
a user data rate that is different from the servo data rate. The actuator positions
the transducer head in response to a control effort signal generated by the sampled
servo controller based on the servo information.