Capacity Planning

Planning for Spikes

The site’s involvement in the Microsoft® Windows® 95 launch led to a surge of activity inside Microsoft, as product and marketing groups added content to it. During 1996, the number of hits per month on the site grew from 118 million to over 2 billion (it is now considerably higher). The product groups’ increased focus on Web-based marketing has fed the ramp-up, as additional users access more content on the site.

Beyond continuing growth and regular periods of peak usage, irregular spikes and special events place much larger burdens on many Web sites and servers. For Microsoft, many of these coincide with software product releases. The release of Microsoft® Internet Explorer 4.0 in October of 1997 is a good example: In one week, more than 2 million users downloaded an average of 18 MB each. Peak usage exceeded 6 terabytes per day.

While it is true that Microsoft’s site has some special requirements, companies of every size need to plan for spikes, which can occur when they start a new ad campaign, appear in a news article, or are linked to a popular Web site. Even a single Web server connected only to a small LAN can experience spikes in activity. However, if the server supports only a small number of clients and their needs are not urgent, the impact won’t be catastrophic. At the same time, if it is important to the enterprise that even a few of those clients be able to access the Web server without delay under any circumstance, or if it is crucial that the site be available all the time, the site manager make sure that it has the necessary capacity and reliability.