DocumentCode :
1950381
Title :
A Performance Model of Zoned Disk Drives with I/O Request Reordering
Author :
Lebrecht, Abigail S. ; Dingle, Nicholas J. ; Knottenbelt, William J.
Author_Institution :
Dept. of Comput., Imperial Coll. London, London, UK
fYear :
2009
fDate :
13-16 Sept. 2009
Firstpage :
97
Lastpage :
106
Abstract :
Disk drives are a common performance bottleneck in modern storage systems. To alleviate this, disk manufacturers employ a variety of I/O request scheduling strategies which aim to reduce disk head positioning time by dynamically reordering queueing requests. An analytical model of this phenomenon is best represented by an M/G/1 queue with queue length dependent service times. However, there is no general exact result for the response time distribution of this variety of queue with generalised service time distributions. In this paper, we present a novel approximation for the response time distribution of such a queue. We then apply this method to the specific case of a zoned disk drive which implements I/O request reordering. A key contribution is the derivation of realistic service time distributions with minimised positioning time. We derive analytical results for calculating not only the mean but also higher moments and the full distribution of I/O request response time. We validate our model against measurements from a real disk to demonstrate the accuracy of our approximation.
Keywords :
disc drives; queueing theory; scheduling; I/O request reordering; I/O request scheduling strategies; M/G/1 queue; disk head positioning time; dynamically reordering queueing requests; generalised service time distributions; realistic service time distributions; response time distribution; zoned disk drives; Analytical models; Delay; Disk drives; Educational institutions; Job shop scheduling; Manufacturing; Predictive models; Processor scheduling; Queueing analysis; Scheduling algorithm; Queueing theory; stochastic modelling; storage systems;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Quantitative Evaluation of Systems, 2009. QEST '09. Sixth International Conference on the
Conference_Location :
Budapest
Print_ISBN :
978-0-7695-3808-2
Type :
conf
DOI :
10.1109/QEST.2009.31
Filename :
5290855
Link To Document :
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