The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 17, 1998
Filed:
May. 01, 1996
Wing Yee Au, Sunnyvale, CA (US);
Quantum Corporation, Milpitas, CA (US);
Abstract
A method for reordering a queue of disk storage input/output (I/O) transfer commands for a hard disk drive. 'Lead time' latencies are calculated for the commands in the queue with respect to the active command. The command with the least lead time latency is selected and promoted to first in the queue. Lead time is seek time plus rotational latency. Lead time may be calculated as the time required for n revolutions of the disk, where the seek time is greater than that time, but less than that required for n+1 revolutions of the disk, plus the rotational time that is required to move from the ending angular position of the active command to the beginning angular position of the subsequent command. In a preferred embodiment, the calculations of lead time are performed in two stages. The first stage determines the beginning and ending physical locations of the I/O transfers for the commands in the queue. These locations do not change for a command and thus these calculations need be performed only once per command. The second stage determines the lead time for each command in the queue with respect to the active command. These values change for each active command and thus must be determined for each command in the queue every time a new command becomes active.