Soraya Zertal

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A workload analysis technique is presented that processes data from operation type traces and creates a Hidden Markov Model (HMM) to represent the workload that generated those traces. The HMM can be used to create representative traces for performance models, such as simulators, avoiding the need to repeatedly acquire suitable traces. It can also be used(More)
A queueing model is developed for a multiRAID storage system implemented on modern zoned disks, using fine, accurate access time functions. An extension of a previous analytical model that utilizes Fork-Join composition of M/G/1 queues, it describes zoning directly in terms of the probability distributions or moments of the model’s components, such as seek(More)
Flash memory is becoming an increasingly important storage component among non-volatile storage devices. Its cost is decreasing dramatically, which makes it a serious competitor of disks and a candidate for enterprise-tier storage device of the future. Consequently, there is an urgent need for models and tools to analyse its behaviour and evaluate its(More)
A recent queueing-based modelling methodology of RAID systems compared the mean disk access times of the two most common variants, RAID0-1 and RAID5, as well as a multi-RAID system in which they coexist. Accesses to multiple disks occur concurrently for each logical (user) request and complete only when every disk involved has completed. The models(More)
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(More)
Embedded multi-core architectures will require a higher bandwidth and scalable Networks on Chip (NoC) to sustain an increasingly demanding communication load in both image and signal processing areas. Corner turns (or matrix transpose) are frequently used in such applications and require special attention due to their all-to-all communications patterns. To(More)
A model of bus contention in a Multi-RAID storage architecture is presented. Based on an M/G/1 queue, the main issues are to determine the service time distribution that accurately represents the highly mixed input traffic of requests. This arises from the coexistence of different RAID organisations that generate several types of physical request(More)