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Evaluating Server System Capacity

The widespread use of the World Wide Web and related applications places interesting performance demands on network servers. The ability to measure the effect of these demands is important for tuning and optimizing the various software components that make up a Web server. To measure these effects, it is necessary to generate realistic HTTP client requests. Unfortunately, accurate generation of such traffic in a testbed of limited scope is not trivial. In particular, the commonly used approach is unable to generate client request-rates that exceed the capacity of the server being tested even for short periods of time. This paper examines pitfalls that one encounters when measuring Web server capacity using a synthetic workload. We propose and evaluate a new method for Web traffic generation that can generate bursty traffic, with peak loads that exceed the capacity of the server. Finally, we use the proposed method to measure the performance of a Web server.

Internet Application Developer evaluates network performance periodically by taking snapshots data of the past year at three-to-six month intervals.

Evaluations require analyzing 1) system reports 2) performance reports from third party vendors, 3) specialized utilities designed to monitor system resource usage, 4) bandwidth loads along official communication paths, 4) emails from user complaining about slow web page display

Internet Application Developer determines the anticipated performance requirements

A Marketing campaign will soon begin that may increase visits to the site by a factor of ten, or the site will be adding streaming audio and video.

Internet Application Developer consults with software vendors to evaluate capacity to handle a given load, such as the typical number of visitors per minute

Transaction throughput is a description measure used to determine a system's capacity to handle a given load, such as the typical number of visitors per minute

Internet Application Developer consults with hardware vendors to evaluate specifications for various platforms and related computer equipment.

App Dev consults with network vendors to evaluate specifications for routers, firewalls, hubs.

Vendors discuss how their products might help your project goals. Their advice may be helpful because they are familiar with the issues you are facing, but keep in mind that their suggestions may be slanted towards their own products. For this reason, you should speak with multiple vendors.

After you talk to several vendors and analyze the information gathered, you will be able to gain a balanced perspective.