Web servers have a way of underperforming when you need them the most, bogging down when deluged with high traffic volume. Users accessing your Web site then have to deal with painfully slow response times and are likely to abandon your site before all the page elements have loaded. Rather than inadequate system hardware, the custom code and batch files written in CGI, SQL, C, or Perl (or a combination of these) that Web servers have to process often cause slow performance. The situation is exacerbated with Internet commerce because a Web server must complete a transaction with another server.
Adding faster drives and more memory solves performance problems only temporarily. As your site gets larger and more popular, its performance will continue to decline. Therefore, the best way to speed Web server response time is to distribute the workload across multiple servers, also known as server clusters.
The easiest way to manage clusters is to employ a load-balancing router, such as the Equaliser E250 from Coyote Point. The E250 model, which shipped in March, is designed for T1 environments. Coyote Point offers other Equaliser models for T3 and 100Mbps Ethernet environments.
Equaliser is essentially a Pentium II-based PC running a custom version of Berkeley Software Distribution Unix and enclosed in an industrial 4U enclosure. Although it has a few minor shortcomings, I recommend Equaliser E250 for a network administrator or Webmaster who wants to maintain the response time of a Web site as it becomes more popular.
One of the few negatives is that Equaliser's power switch is unprotected, an open invitation to anyone who might think turning the unit off would be fun. I also did not see the reason why the unit, which is slightly bigger than a large desktop computer, is so bulky. In response to my concerns, Coyote Point says that a new 3U case coming out shortly will have a protected power switch and a smaller footprint.
I completed initial configuration, such as assigning internal and external IP addresses, via a terminal connection, but was able to finish the configuration using a Web browser. Equaliser uses a Network Address Translation subsystem to distribute incoming client requests among the available servers. I liked that I could configure a second Equaliser as a backup unit in case the first one failed.
Early load-balancing routers used a round-robin method of distributing incoming client requests to servers, but most new devices have more than one way of distributing the load. The methods may be similar in name, but the code behind them is unique to every load balancer.
Equaliser E250 has six different load distribution methods: round robin, weighted round robin, adaptive, fastest response, least connections, and server agent.
Equaliser E250 is more streamlined than previous versions, which allows for a greater overall load. In addition, Equaliser E250 has hooks for a new software add-on called Envoy, which is an intelligent geographic load balancer. In conjunction with Equaliser's server load balancing, it provides scalability and availability across multiple server clusters located anywhere in the world. An Envoy-enabled Equaliser routes incoming traffic among the widely distributed servers, using criteria such as network topology, site availability, and performance to determine which server is best equipped to handle the next request.
In addition to specifying a load-balancing method, I was able to configure "sticky" connections, which allow clients to connect to the same server for each request during a predefined length of time. These types of connections are necessary, for example, when using Secure Sockets Layer protocol or any other secure client-to-host connection. I also liked Equaliser E250's cluster statistic charts, which help network administrators monitor server status and activity.
Equaliser compares favorably with load-balancing routers such as Cisco Local Director and F5 Labs BIG/ip, offering the same or better features and performance at a better price. For instance, Equaliser E250 offers Web-based configuration, while Local Director comes with a command-line interface as the default. Likewise, in a similar configuration, BIG/ip costs thousands of dollars more.
If your Web site is suffering from slow response times, you should consider the Equaliser E250 as a solution. Compared to other load balancers on the market, Equaliser is easy to install and configure and is very reasonably priced.
The bottom line: very good.
Summary: This server load-balancing router improves Web server performance by intelligently distributing client requests across a server cluster. Compared to its competitors, Equalizer is easy to install and configure, and priced reasonably.
Business Case: If you have a rapidly growing Web site whose performance is suffering, the solution may not lie in upgrading the server, but rather in investing in the Equalizer load-balancing product.
+ Easy to install and configure
+ Web-based configuration
- Unprotected power switch
- Relatively large footprint
Cost: E250 is $US3,995; Envoy is $2,500. This is less expensive than other load balancers such as Local Director and BIG/ip.
Platform: Works with any TCP/IP server