US Patent 10379760 Data storage device opportunistically refreshing data

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks. A first degradation metric is maintained for a first segment of a first track, wherein the first degradation metric indicates a degree of degradation for data recorded in the first segment. The first degradation metric is processed to select an access command from a plurality of access commands including a read command to read the first segment. The selected access command is executed to access the disk.