Western Digital Technologies, Inc.

Quoc Dang

Michael Stephen Rothberg

Virgil V Wilkins

Tsun Y Ng

Ralph H Castro

Kenny T Coker

Mark F Vallis

Joseph C S Liu

Gary K Laatsch

Daniel A Hanson

Sharon H Yu

A disk drive is disclosed comprising a disk, a head actuated over the disk, a host interface for receiving disk access commands from a host, a command queue for queuing the disk access commands, and a stream detection engine for evaluating the disk access commands to detect a plurality of streams accessed by the host. The stream detection engine maintains a stream data structure for each detected stream, wherein the stream data structure comprises a frequency counter for tracking a number of disk access commands associated with the stream out of a predetermined number of consecutive disk access commands received from the host. A disk controller selects one of the streams for servicing in response to the frequency counters.

Disk drive employing stream detection engine to enhance cache management policy

A disk drive is disclosed comprising a disk having a plurality of tracks, a head actuated over the disk, and control circuitry for servicing an access command received from a host, wherein the access command identifies at least one of the tracks. The control circuitry identifies a band of tracks associated with the access command, maintains a counter for tracking an amount of time the head is within the band of tracks, and moves the head out of the band of tracks in response to the counter to facilitate wear prevention.

Disk drive implementing wear prevention in a high frequency access band of tracks

The present invention relates to a disk drive including a cache memory having a plurality of sequentially-ordered memory clusters for caching disk data stored in sectors (not shown) on disks of a disk assembly. The disk sectors are identified by logical block addresses (LBAs). A cache control system of the disk drive comprises a cluster control block memory, having a plurality of cluster control blocks (CCB), and a tag memory, having a plurality of tag records, that are embedded within the cache control system. Each CCB includes a cluster segment record with an entry for associating the CCB with a particular memory cluster and for forming variable length segments of the memory clusters without regard to the sequential order of the memory clusters. Each tag record assigns a segment to a continuous range of LBAs and defines the CCBs forming the segment. Each segment of the memory clusters is for caching data from a contiguous range of the logical block addresses. The cache control system efficiently exploits available memory clusters for responding to host commands.

Cluster-based cache memory allocation

A disk drive is disclosed comprising a disk for storing initial host requested (IHR) data requested by a host computer during a start-up process of the host computer, a head actuated radially over the disk, and a non-volatile semiconductor memory (NVSM) for caching at least part of the IHR data. The disk drive transmits the cached IHR data from the NVSM to the host computer during the start-up process thereby avoiding the delay associated with initializing the mechanics of the disk drive as well as conserving battery power for mobile applications.

Disk drive caching initial host requested data in non-volatile semiconductor memory to reduce start-up time of a host computer

A disk drive is disclosed comprising a disk and a semiconductor memory comprising addressable locations for staging and caching data, wherein each addressable location having an allocation status. When a large write command is received from a host to write write-data to the disk, a disk controller dynamically allocates a plurality of the addressable locations relative to the size of the write command and the allocation status of the addressable locations. The write-data received from the host is stored in the dynamically allocated addressable locations while concurrently reading the write-data from the dynamically allocated addressable locations and writing the write-data to the disk. The dynamically allocated addressable locations are re-used for storing write-data received from the host after writing the write-data to the disk.

Disk drive for dynamically allocating memory accessed concurrently by a host interface and a disk interface to facilitate large host commands

The present invention may be embodied in a cache control method for caching disk data in a disk drive configured to receive commands for both streaming and non-streaming data from a host. A lossy state record is provided for memory segments in a cache memory. The lossy state record allows hosts commands to be mixed for streaming and non-streaming data without flushing of cache data for a command mode change.

Cache control method and system for mixed streaming and non-streaming data

The present invention relates to a disk drive including a cache memory having a plurality of sequentially-ordered memory clusters for caching disk data stored in sectors (not shown) on disks of a disk assembly. The disk sectors are identified by logical block addresses (LBAs). A cache control system of the disk drive comprises a cluster control block memory, having a plurality of cluster control blocks (CCB), and a tag memory , having a plurality of tag records, that are embedded within the cache control system. Each CCB includes a cluster segment record with an entry for associating the CCB with a particular memory cluster and for forming variable length segments of the memory clusters without regard to the sequential order of the memory clusters. Each tag record assigns a segment to a continuous range of LBAs and defines the CCBs forming the segment. Each segment of the memory clusters is for caching data from a contiguous range of the logical block addresses.

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Brea, CA, United States of America

Quoc Dang