Abstract: The periodic component of a timing mark position error of a self-servo write pattern on a disk of a disk drive is determined based on measurements that are made of the timing mark position error at selected radial track locations. The determined periodic component of the timing mark position error is then removed based on the radial location on the disk.

Abstract: A method and apparatus is provided which reduces the equipment and time requirements for hard disk drive performance testing during manufacturing. This invention executes self-contained performance testing code that resides within the drive's manufacturing firmware, rather than relying on external testers. The invention involves exercising the drive's enqueue, dequeue, and command execution firmware, as well as the physical process of reading and writing data by simulating the host interface in code. The invention enqueues commands that typify the desired workload, allows a command ordering algorithm to sort the commands for execution, and allows the drive side code to execute the commands just as if an external host interface were attached. The invention is advantageous because the performance testing can be done by only applying power to the drive. The present invention also lends itself to performance tuning that can be done in manufacturing, to reduce drive-to-drive performance variations.

Abstract: A method for operating a disk drive having timing marks (TMs) on the disk that are chosen to reduce the probability of misidentification of a TM in the presence of read errors. The disk drive searches for TMs within a fixed TM search window which extends past the TM on the disk. A TM preferably maximizes the post-shift sliding distance for m post-shifts of the TM pattern, where m corresponds to the TM search window boundary. In this manner, the probability of a misidentification of the TM due to a post-shift having a small distance from the TM pattern is reduced. The TM pattern also provides pre-shift error resistance.

Abstract: Provided is a data storage device in which read and write heads can be desirably located with respect to servo tracks from the viewpoint of linearity of a PES on the premise that a read write offset exists. A read write offset value, which is a deviation amount between write and read heads in a radial direction of a disk-shaped storage medium, is set equivalent to an integer number N of servo tracks.

Abstract: The read/write offset between the read head and write head is used to determine the head width ratio between the read head width and write head width. The servo information is written onto the magnetic disk in accordance with the APC value and track pitch that are derived from the determined head with ratio.

Abstract: Provided is a data storage device in which servo track pitch varies within a predetermined region in a radial direction of a disk-shaped storage medium.

Abstract: An adaptive maximum seek velocity clipping technique is employed in a disk drive to reduce head movement power requirements. Separate maximum seek velocities are established for respective categories of access commands, where the categories are defined by seek distance and estimated extra latency. The maximum seek velocity established for each category of access commands reflects actual experience in executing access commands of the given category. The maximum seek velocity values for the various categories are stored in a maximum seek velocity table, which is referred to upon execution of access commands. The inventive power-saving technique may be advantageously applied in conjunction with a probability-based shortest access time first (SATF) command queue ordering algorithm.

Abstract: A command queue is maintained in a disk drive. The command queue includes a plurality of access commands that are awaiting execution. The command queue is sorted to provisionally select one of the plurality of access commands as the next command to be executed. A seek start deadline is calculated for the provisionally selected access command based on an estimated extra latency of the provisionally selected access command. A seek operation with respect to the provisionally selected access command is deferred based on the calculated seek start deadline, to await arrival at the disk drive of a new access command. If the new access command arrives at the disk drive prior to the seek start deadline, the respective estimated access times for the provisionally selected access command and the newly arrived access command are compared to select one of the two access commands for execution.