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Performance analysis of an iSCSI-based unified storage network
FU Xiang-lin, ZHANG Kun, XIE Chang-sheng
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(1): 1-7.
https://doi.org/10.1631/jzus.2004.0001
In this paper, we introduced a novel storage architecture \"Unified Storage Network\", which merges NAC (Network Attached Channel) and SAN (Storage Area Network), and provides the file I/O services as NAS devices and provides the block I/O services as SAN. To overcome the drawbacks from FC, we employ iSCSI to implement the USN(Unified Storage Network). To evaluate whether iSCSI is more suitable for implementing the USN, we analyze iSCSI protocol and compare it with FC protocol from several components of a network protocol which impact the performance of the network. From the analysis and comparison, we can conclude that the iSCSI is more suitable for implementing the storage network than the FC under condition of the wide-area network. At last, we designed two groups of experiments carefully.
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Using multi-class queuing network to solve performance models of e-business sites
ZHENG Xiao-ying, CHEN De-ren
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(1): 31-39.
https://doi.org/10.1631/jzus.2004.0031
Due to e-business\'s variety of customers with different navigational patterns and demands, multi-class queuing network is a natural performance model for it. The open multi-class queuing network (QN) models are based on the assumption that no service center is saturated as a result of the combined loads of all the classes. Several formulas are used to calculate performance measures, including throughput, residence time, queue length, response time and the average number of requests. The solution technique of closed multi-class QN models is an approximate mean value analysis algorithm (MVA) based on three key equations, because the exact algorithm needs huge time and space requirement. As mixed multi-class QN models, include some open and some closed classes, the open classes should be eliminated to create a closed multi-class QN so that the closed model algorithm can be applied. Some corresponding examples are given to show how to apply the algorithms mentioned in this article. These examples indicate that multi-class QN is a reasonably accurate model of e-business and can be solved efficiently.
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Large eddy simulation of the gas-particle turbulent wake flow
LUO Kun, JIN Han-hui, FAN Jian-ren, CEN Ke-fa
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(1): 106-110.
https://doi.org/10.1631/jzus.2004.0106
To find out the detailed characteristics of the coherent structures and associated particle dispersion in free shear flow, large eddy simulation method was adopted to investigate a two-dimensional particle-laden wake flow. The well-known Sub-grid Scale mode introduced by Smagorinsky was employed to simulate the gas flow field and Lagrangian approach was used to trace the particles. The results showed that the typical large-scale vortex structures exhibit a stable counter rotating arrangement of opposite sign, and alternately form from the near wall region, shed and move towards the downstream positions of the wake with the development of the flow. For particle dispersion, the Stokes number of particles is a key parameter. At the Stokes numbers of 1.4 and 3.8 the particles concentrate highly in the outer boundary regions. While the particles congregate densely in the vortex core regions at the Stokes number of 0.15, and the particles at Stokes number of 15 assemble in the vortex braid regions and the rib regions between the adjoining vortex structures.
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20 articles
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