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Using Bulk Arrivals to Model I/O Request Response Time Distributions in Zoned Disks and RAID Systems

Abigail Lebrecht, Nicholas J. Dingle, Peter G. Harrison, William J. Knottenbelt, Soraya Zertal

Conference or Workshop Paper
4th International Conference on Performance Evaluation Methodologies and Tools (VALUETOOLS 2009)
September, 2009
DOI 10.4108/ICST.VALUETOOLS2009.7787
Abstract

Useful analytical models of storage system performance must support the characteristics exhibited by real I/O workloads. Two essential features are the ability to cater for bursty arrival streams and to support a given distribution of I/O request size. This paper develops and applies the theory of bulk arrivals in queueing networks to support these phenomena in models of I/O request response time in zoned disks and RAID systems, with a specific focus on RAID levels 01 and 5. We represent a single disk as an M^{X}/G/1 queue, and a RAID system as a fork-join queueing network of M^{X}/G/1 queues. We find the response time distribution for a randomly placed request within a random bulk arrival. We also use the fact that the response time of a random request with size sampled from some distribution will be the same as that of an entire batch whose size has the same distribution. In both cases, we validate our models against measurements from a zoned disk drive and a RAID platform.

Notes

Electronic proceedings only

http://dl.acm.org/citation.cfm?id=1698853

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Information from pubs.doc.ic.ac.uk/valuetools2009-ipods.