Capacity Planning
Capacity Planning |
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The task force began to look at the objects—text files, graphics, and other files that make up individual Web pages—that were being called by the servers. Some of those objects are housed in the Properties Database (PD), which receives and stores individual user preferences: news headlines, personalized home-page options, and stock quotes, for example. Through a process of elimination, the task force came to suspect the Properties Database of being the main culprit behind the ongoing slowdowns and failures. All of the servers were drawing on the same central repositories or databases for page elements, like many wells drawing on a common aquifer. In other words, the problem was external to the servers themselves; adding more of them just made it worse, because doing so only increased the loading on the bottlenecked component.
Part of the solution was to cut down the number of requests to that particular set of databases. New, less demanding ways of personalizing pages were developed, and the server software was adjusted to work better for the rapidly increasing numbers of viewers using the site. In addition, the database servers were moved physically closer to the Web servers in order to allow the team to eliminate intervening routers and other hardware. Meanwhile, the team continued to examine the entire process of creating Web pages and of serving them to visitors.