LIP6 1997/002
- Reports
Approche analytique pour l'étude des performances de serveurs multimédias multidisques en grappe - H.Kaddeche, A.-L.Beylot, M.Becker
- 22 pages - 03/14/1997- document en - http://www.lip6.fr/lip6/reports/1997/lip6.1997.002.ps.gz - 124 Ko
- Contact : kaddeche (at) nulletna.int-evry.fr
- Ancien Thème : RP
- Keywords : multimedia servers, clustered architecture, analytical models, performance evaluation, disk, switch
- Publisher : Emmanuel.Anique (at) nulllip6.fr
There are many different future multimedia applications requiring servers which are able to provide video sequences on-demand to simultaneous users through a high speed network. A convenient design for these servers seems to be a clustered architecture including a set of storage nodes (with a local disk array) and a set of delivery nodes, those two sets being interconnected by a switch. Video files are shared into blocks and distributed on the disks.
In this paper an analytical model is designed for the study of these servers. We present the detailed modeling of the different components of the system and a final simplified model. The model allows a quick dimensioning of the operating parameters. It allows to save expensive simulations and to avoid rare event problems. The performance evaluation study focuses on the quality of transmission characterized by the probability of happening of a break in the delivery of blocks. A brief transmission break occurs when the expected block is not loaded in time in the delivery node that should manage its transmission to the external network. If the block is late, it will not be transmitted and this will result in a short break at the user end. The performance criterion considered is the probability of delay for a block. This probability depends on the distribution of the loading time of a block : the response time of the disk plus the response time of the switch. In the final simplified model, the disks are modeled by M/D/1 queues and the switch is modeled by a constant delay.
The proposed model is validated through extensive simulations of an accurate queueing network model. The dimensioning of the system is then derived from the model results.
In this paper an analytical model is designed for the study of these servers. We present the detailed modeling of the different components of the system and a final simplified model. The model allows a quick dimensioning of the operating parameters. It allows to save expensive simulations and to avoid rare event problems. The performance evaluation study focuses on the quality of transmission characterized by the probability of happening of a break in the delivery of blocks. A brief transmission break occurs when the expected block is not loaded in time in the delivery node that should manage its transmission to the external network. If the block is late, it will not be transmitted and this will result in a short break at the user end. The performance criterion considered is the probability of delay for a block. This probability depends on the distribution of the loading time of a block : the response time of the disk plus the response time of the switch. In the final simplified model, the disks are modeled by M/D/1 queues and the switch is modeled by a constant delay.
The proposed model is validated through extensive simulations of an accurate queueing network model. The dimensioning of the system is then derived from the model results.