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In recent years there is a rapid increase of traffic to a given web server within a short time as the number of Internet users increases, and such a phenomenon is called a flash crowd. Once flash crowds occur in the web server, a response rate decreases or the web server may crash as the load increases. We propose a load reduction system, which prevents excessive accesses and stably delivers content...
The paper describes how to model and control performance of a trusted web server using Feedback Error Learning and H∞ control theory. Web server load may experience enormous variations and unpredictability. Existing web servers are difficult to achieve performance guaranties in such environment. One of challenges in web server research is how to model non-linearity computing systems. We demonstrate...
Motivated by the high variation in transmission rates for document transfer in the Internet and file down loads from web servers, we study the buffer content in a queue with a fluctuating service rate. The fluctuations are assumed to be driven by an independent stochastic process. We allow the queue to be overloaded in some of the server states. In all but a few special cases, either exact analysis...
Cluster is one of the most popular techniques to resolve the problem, in which the scalability of Internet servers is becoming more and more important. However, as well known, Web server cluster schemes have a lot of disadvantages, such as lack of self-organization, existing bottleneck of system. This paper proposes a model of server cluster based on mobile agent. To develop the capability of load-reassignment...
Energy efficiency is a very important issue to keep the "Green" Earth, especially in recent years. We have to save the energy consumption anywhere and anytime, including a large set of servers, such as servers in the Google company. In our research, we mainly consider one important energy-electric power. In our previous work, we discussed the difference energy model in cluster servers, and...
Searching for examples to encourage and motivate students in a subject is not a trivial task. Future Computer Science and Telecommunications Engineers tend to look at Automatic Control reluctantly. They do not relate their working life to it. But, if we blend examples from two areas: telecommunications and control, maybe we can change their minds. These engineers work with web servers: systems that...
The administration of clusters is an exhausting job. Particularly, allocating the resources of the clusters by hand can easily become unmanageable because the processing requirements can change very quickly in a dynamic environment such as the Internet. A solution to solve this problem is to use a dynamic architecture for self-reconfiguration of the clusters. In a previous work, we have proposed the...
Power management of web server clusters have become a critical design issue because of its increasing power consumption and cooling cost. Current web server clusters are normally designed to have a performance capacity to handle peak loads, where all servers are fully utilized (turned on and running at maximum frequency). But in practice, peak load conditions rarely or never happen and most of the...
Allocating resources in a Web server cluster is usually performed nowadays by a cluster administrator. However, due to the dynamics of the Internet as far as the use of resources is concerned, such a task may be considered critical and inefficient if accomplished manually. This paper presents an architecture that performs an automatic dynamic reconfiguration using a multi agent system. The architecture,...
We present a simulation model of a Web cluster which includes important aspects of the hardware, operating and communication systems as well as the application layer for realistic performance evaluations. We formulate the model in UML taking into account both architectural and behavioral aspects and apply detailed system-level measurements at low loads for determining parameters. Measured one-way...
Before placing a web based application in the real servers of the real world with millions of users and going to serve them, it is needed to examine the functionality of the application which is under real work load stress to evaluate server and application for final conditions. This paper is focused on modeling of the user behavior by using data mining methods and extracting different types of application...
Transient overload is a short term event characterized by a sudden and unexpected rise of the arrival rate in a Web server. Transient overload events in Web servers have been observed more frequently as the number of Internet users grows and the Web services become more popular. This paper deals with the non-trivial problem of generating overload for Web server testing. In this paper we present a...
Accurate performance metric models are the key to Web capacity planning related problems. Due to the complexity of Web systems, analytical modeling without integrating the performance testing process is not enough to get accurate metric models. To integrate performance testing and analytical modeling in a systematic way, a Web performance modeling process is presented based on the methodology of learning...
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