Western Digital Technologies, Inc.

Ming Ying Wang

Gregory B Thelin

Yanning Liu

Duc T Phan

Chuanwen Ji

A disk drive is disclosed comprising a head, a disk surface, and a voice coil motor (VCM) and a microactuator operable to actuate the head over the disk surface. A sensitivity of the microactuator is periodically measured over a lifetime of the microactuator. Each measured sensitivity is stored in a timeline log, wherein the timeline log represents a degradation curve of the microactuator over the lifetime of the microactuator.

Disk drive performing lifetime logging of microactuator sensitivity

A disk drive is disclosed comprising a cache buffer for caching data written to the disk and data read from the disk, the cache buffer comprising a plurality of cache segments linked together to form a plurality of cache links. At least one segment attribute is associated with each cache segment, including an allocation state, and at least one link attribute is associated with the segment attributes within each cache link. When a host command is received from a host computer, the link attributes are evaluated to allocate cache segments for a cache link associated with the host command.

Disk drive maintaining a cache link attribute for each of a plurality of allocation states

A disk drive is disclosed which receives a read command from a host computer, the read command comprising a command size representing a number of blocks of read data to read from the disk. A number M of cache segments are allocated from a cache buffer, wherein each cache segment comprises N blocks. The number M of allocated cache segments is computed by summing the command size with a predetermined default number of read-ahead blocks to generate a summation, and integer dividing the summation by N leaving a residue number of default read-ahead blocks. In one embodiment, the residue number of default read-ahead blocks are not read, in another embodiment the residue number of default read-ahead blocks are read if the residue number exceeds a predetermined threshold, and in yet another embodiment the number of read-ahead blocks is extended so that the summation divides evenly by N.

Disk drive adjusting read-ahead to optimize cache memory allocation

A disk drive is disclosed comprising a disk having a plurality of tracks, each track comprising a plurality of blocks. A semiconductor memory comprises a cache buffer having a plurality of segment pools, each segment pool comprising a plurality of cache segments, each cache segment comprises at least one block, and the number of blocks in each cache segment varies between segment pools. When a host command is received, the command size is compared to a threshold in order to allocate a cache segment from a first segment pool or a second segment pool.

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Mission Viejo, CA, United States of America

Ming Ying Wang