Patent ID: 8587889

Claim:
A disk storage apparatus comprising: a write module configured to move a write head to a first track on a disk, and to record data in the first track with a shingled write operation; and a controller configured to control operation of the write module, wherein the controller comprises: a first acquiring module configured to acquire a first positioning error made when the write head is moved to the first track; and a second acquiring module configured to acquire a second positioning error made when data is recorded in a second track from which data is erased in part as the shingled write operation is performed at the first track, wherein the controller is configured to determine an off-track threshold value for securing a valid track width in the first track and a valid track width in the second track using the first positioning error and the second positioning error, and to inhibit the write module from writing data if the first positioning error exceeds the off-track threshold value, and wherein the controller is further configured to: inhibit the write module from recording data if the absolute value of the first positioning error exceeds the off-track threshold value: acquire a dynamic threshold value corresponding to an off-track limit value tolerable for recording data, based on the second positioning error, if the write head is positioned off toward the second track because of the positioning error of the first track even if the absolute value of the first positioning error does not exceed a prescribed threshold value; and inhibit the write module from recording data if the absolute value of the first positioning error exceeds the dynamic threshold value.