Scaling Your E-BUSINESS

Software Magazine, Feb, 2001 by Daniel Menasce, Virgilio Almeida

DELAYS ON THE INTERNET frustate customers and cost e-businesses billions of dollars. While the causes of these delays vary, overloaded networks and servers are the most common ones. The viability of e-business depends on the ability of the IT infrastructure to offer timely and reliable services.

Yet the news is full of reports of horrendous performance by high-profile sites unprepared for an overwhelming and unexpected surge of users. Britannica.com and Victoria's Secret have been well-publicized examples. Another example is the online recruitment firm hotjobs.com, which spent $2 million in TV ads during the 1999 Super Bowl, and subsequently drew hundreds of thousands of visitors to its Web site. The company, however, had neglected to plan the capacity of the site before inviting millions of potential visitors. As a result, many visitors were shut out.

Load spikes and traffic bursts are facts of life in the operation of an e-business. In Election 2000, for example, sites like ABC, Yahoo, Fox, CNN, and others saw their traffic increase by 300%.

In the e-tail arena, e-commerce sites experienced in 2000 the same influx of shoppers the day after Thanksgiving--traditionally one of the busiest shopping days--as brick-and-mortar retailers, according to NetRatings, Milpitas, Calif., with spikes in apparel and consumer electronics in particular. Apparel sites were the hottest category, with an overall rise of 68% on that Friday following Thanksgiving, as compared to the rest of the week. Landsend.com skyrocketed 93%, followed by Gap.com, 86%, and Spiegel.com, 85%. Consumer electronics sites rose 46%, with CircuitCitycom jumping 126% in unique audience at home on Friday. Outpost.com rose 48%, and 800.com increased 40% in traffic.

To accommodate these types of traffic spikes, e-businesses must be able to build architectures that can scale many times in a short period of time. Many e-tailers have learned this the hard way, however. According to Jupiter Research, New York City, slow site performance plagued e-tailers in 1999 and was considered the third top online shopping problem during Christmas. During the most recent holidays, many sites briefly shut down due to excess traffic.

Developing an infrastructure that is rapidly scalable across local and wide areas networks, in a cost-effective way, requires a good understanding of system capacity modeling and planning, an area where many e-businesses are apparently lacking. This article details the most common causes that prevent a site from scaling up, as well as presents a road map to scalability--a capacity planning methodology. A reference model for e-business (sec Figure, this page) provides a framework for the scalability analysis methods discussed here. A capacity planning approach based on this reference model offers a way to determine scalability problems and to plan alternatives for scaling an e-business system.

Three Requirements

Web-based services are offered to potentially tens of millions of users by hundreds of thousands of servers (i.e., content providers and service providers). Users and servers are connected through the Internet. These users or customers count on being able to access any service, anytime. Customers' increasing reliance on information-based services means that e-businesses, and the services they provide, must meet three requirements: availability, scalability, and cost-efficiency.

Availability means that users and customers can count on being able to access any Web service from anywhere, anytime, regardless of the load at both the Web site and the network. Availability also means that services are provided with quality; i.e., short and predictable response time. Scalability means that servers should be able to provide services to all potential customers, whose number is fast-growing and unknown for a company. Cost-effectiveness means that quality of Web services, respresented by availability and fast response times, should be achieved with an IT infrastructure that minimizes cost.

The Scalability Problem

The quality of service of e-business sites depends on many interrelated factors, such as site architecture, network capacity, and system software structure. Unpredictable public behavior compounds the complexity of an e-business site. Usage patterns can change overnight, with spikes in demand occurring for several reasons. For instance, breaking news always causes bursts of traffic on online editions of major newspapers. Or, when a company runs a marketing campaign, the capacity of its site may be inadequate to support the huge number of visitors who react to the campaign.

All of these characteristics of e-business clearly indicate that quantitative techniques are needed to manage the behavior of online companies and to guarantee quality of service. Mission-critical e-business sites require careful planning and design to ensure that the application delivers reliable and scalable services. Organizations must analyze the entire end-to-end system, plus understand and document the characteristics and performance of applications, servers, networks, load balancers, and firewalls. However, in many cases, scalability cannot be achieved because of the existence of bottlenecks--hardware and software resources that limit overall system performance.