Abstract: A method of measuring a track value is shown. The track value is related to track mis-registration, and is compared to a track value limit to assess a condition of the track. In example embodiments, the track value is determined as a function of multiple position error signals from previous wedges in the track. During a self servo writing operation, the track value and the track value limit are used to selectively perform a recovery action. In example embodiments, the track value limit is dynamically adjusted.

Abstract: Methods and systems are shown that specify using group counters and track counters to reduce the need for adjacent-track-erasure (ATE) refresh. A group threshold may be used to monitor the number of write operations to a group. The group threshold may be used to determine when it is necessary to monitor the write operations to the tracks in a group on an individual basis.

Abstract: Methods and systems are shown that specify at least one low track-per-inch (TPI) region and at least one normal TPI region on a disk. The low TPI region may be used to store information that may be rewritten frequently. The normal TPI region may be used to store information that may be rewritten less frequently. The low TPI region may reduce the need for adjacent-track-erasure (ATE) refresh.

Abstract: A method for assembling a disk drive includes placing disks on a spindle, and pivoting a turbulence reduction plate to a position between the disks on the spindle. The turbulence reduction plate is placed on a pivot associated with the housing and then rotated into position. The turbulence reduction plate is attached to the housing and a cover is placed onto the housing to form a disk enclosure which also encloses the turbulence reduction plate.

Abstract: Methods and devices are shown that identify suitable second data operations after experiencing an off track event in a first data operation and perform the second data operations before correcting an off track event. Methods and device as shown provide increased efficiency in a hard disk drive. Time that normally would be wasted waiting for the read/write head to spin around for another try to correct an off track error is used to complete other nearby operations.

Abstract: A method of self servo writing is shown. In example embodiments, spirals or other indexing patterns can be written entirely within a hard disk drive, thus enabling self servo writing of the entire disk surface. Increased accuracy in spiral writing in turn increases the track density achievable using self servo writing techniques. One example method includes writing a first indexing pattern, then using the first indexing pattern to servo and write an adjacent second indexing pattern. Other example methods further include the use of back electromotive force (EMF) to increase accuracy in writing patterns such as spirals.

Abstract: A method for locating a track on a disk surface having a plurality of wedges of servo information includes demodulating servo information for a first servo wedge, and determining a correction factor for a written in repeatable runout for the servo information for the first servo wedge before demodulating servo information for a second servo wedge. A machine-readable medium provides instructions that perform the above method. A disk drive includes a processor disk that performs the above method and generates a signal to position a transducer over a desired track.

Abstract: A disk drive apparatus is shown that provides multi-tasking of firmware and hardware separately. A shared data structure is shown that permits queuing of multiple task requests and storing of multiple task results for later use, decreasing a need for wait time between components such as disk drive firmware and hardware. Further efficiencies are provided, including power saving modes when higher power disk drive components are not in use.

Abstract: According to one embodiment, a disk drive apparatus includes a defect table formed using more than one defect detection standard. Methods and devices are described using different defect detection standards to detect and map defects of different sizes and in specific regions that can affect drive operation. Also, methods and devices are described that provide fast and efficient defect scanning in selected regions due to utilization of error correction systems. Methods are shown where during defect detection a read/write gate assertion is triggered using a servo gate pulse.