Dynamic magnetic information storage or retrieval – Head – Core
Patent
1996-05-01
1998-03-17
Shin, Christopher B.
Dynamic magnetic information storage or retrieval
Head
Core
395438, 395825, 395859, 360 98, 360 48, 369 47, 369178, G06F 1328, G11B 5012
Patent
active
057297185
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.
REFERENCES:
patent: 4232365 (1980-11-01), Englund
patent: 4270154 (1981-05-01), Crawford
patent: 4583166 (1986-04-01), Hartung et al.
patent: 5140683 (1992-08-01), Gallo et al.
patent: 5241546 (1993-08-01), Peterson et al.
patent: 5255136 (1993-10-01), Machado et al.
patent: 5422762 (1995-06-01), Jerbic
patent: 5432922 (1995-07-01), Polyzois et al.
patent: 5581784 (1996-12-01), Tobagi et al.
Abbot et al, "Scheduling I/O Requests with Deadlines: A Performance Evalua", Dec. 5-7, 1990 pp. 116-117, IEEE: Real-Time Systems, 1990 Symposium.
Ng, "Improving Disk Performance via Latency Reduction", Jan. 1991, pp. 22-24, IEEE Transactions on Computers.
Salem, "Performance Evaluation of Movable Head Disk Schedules", Sep. 16-18, 1991 pp. 250-253 Software Engineering for Real Time Systems (IEE Conf. Pub. 344).
IBM Technical Disclosure Bulletin, "Enhanced Disk Task Sequencing", Oct. 1986, pp. 1946-1948, vol. 29, No. 5.
McGraw et al (IBM TDB), "Priority Circuit Servicing Requests Queued by Sector", Nov. 1969, pp. 815-819, vol. 12, No. 6.
Seltzer et al, "Disk Scheduling Revisited", Jan. 1990, pp. 313-323, USENIX Winter 1990 Washington, DC.
Gibson, Redundant Disk Arrays--Reliable, Parallel Secondary Storage, MIT Press, Cambridge MA, .COPYRGT.1992, pp. 17-20: "Lowering I/O Response Time".
Geist & Daniel, "A Continuum of Disk Scheduling Algorithms", ACM Trans. Computer Systems, vol. 5, No. 1, Feb. 1987, pp. 77-92.
Teory & Pinkerton, "A Comparative Analysis of Disk Scheduling Policies", Comm. of the ACM, vol. 15, No. 3, Mar. 1972, pp. 177-184.
Denning, "Effects of Scheduling on File Memory", AFIPS Joint Computer Conference Proc. vol. 30, 1967, pp. 9-21.
Harrison David B.
Perveen Rehana
Quantum Corporation
Shin Christopher B.
LandOfFree
System for determining lead time latency as function of head swi does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for determining lead time latency as function of head swi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for determining lead time latency as function of head swi will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-966605