Method and structure enabling improved native command queueing in a data storage device

摘要

A data storage device accepts read and write commands with absolute command completion times based on queue-depth-of-one (qd=1) execution and stores them in an unsequenced commands memory. These commands are requests to access the data storage device and contain both locations on the storage medium where the data is located and whether the requested operation is read or write. For each pair of first and second commands in the memory, the time between execution of the first command and the second command is calculated and stored. A command selector then reads data from the memory based on a resequencing NCQ algorithm which inserts one or more commands from the command memory into the original qd=1 sequence whenever this insertion will not affect the execution time of commands in the original qd=1 sequence. The resequencing algorithm of the present invention increases IOPS and reduced read head actuator travel and wear.

主权项

1. A data storage device that accepts read and write commands from a host system, comprising:
an unsequenced commands memory, configured to store the read and write commands; a time-distance calculator, configured to calculate the time-distances between every pair of commands stored in the unsequenced commands memory, each pair comprising first and second commands, wherein the time-distance is defined as the minimum possible time between execution of the first command and then the second command; a sequenced commands queue, configured to store commands for processing in a first-in-first-out sequence for processing; a command selector, configured to transfer commands from the unsequenced commands memory to the sequenced commands queue according to a predetermined native command queueing algorithm; and an input/output scheduler, configured to schedule the sequential execution of the commands stored in the sequenced commands queue.