A Performance Model of Zoned Disk Drives with I/O Request Reordering

Provided by: Imperial College London
Topic: Storage
Format: PDF
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 queuing 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 generalized service time distributions. In this paper, the authors present a novel approximation for the response time distribution of such a queue.

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