Still, ServerIron isn't perfect. Many features, including the failover status, are accessible only via the console interfaces, not from IronView or the Web management interface. As with many of the load balancers we tested--WSD Pro and LocalDirector among them--ServerIron provides no mechanism for copying its configuration from one load balancer to another. Large Web-hosting sites undoubtedly will have to devote valuable time to configuring each Web cluster and its servers for each load balancer. And other than the Web management interface's port-indicator LEDs, which automatically update each port's status every few seconds, ServerIron provides no real-time monitoring tools.

HydraWeb Technologies Hydra5000 1.3
HydraWeb, our award winner in last year's comparative review of load balancers, has seen new and improved competition pass it by. Maintaining its dominance of fine-grained server load balancing, HydraWeb continues to use its Multi-Plexor Load Average (PLA) technology as the cornerstone of its load-balancing metrics. For a hardware load balancer, adequate redundancy features and excellent configuration scripts are assets, but the lack of any remote-management utilities or graphical monitoring tools pushes Hydra5000 back into the pack.

Using monitor and keyboard, we followed the initial installation scripts, which prompted us to provide various information concerning the network environment and configuration for the Hydra5000 itself. Each step in the script is accompanied by a short summary of what is being asked and how it relates to the Hydra5000's operation. After completing the base configuration steps, you can continue configuration of the Hydra5000 via the network. No other load balancer's installation scripts were as complete as the Hydra5000's.

The Hydra5000's best feature is its ability to fine-tune the metrics that determine the preferred server for each incoming TCP/IP connection.

Incorporating various weights and administrative additives or offsets, Hydra5000 calculates a PLA for each server in each cluster. The server with the lowest PLA gets the most incoming connections. At first, the various aspects of calculating a PLA are confusing, but with practice and proper research, any administrator can tune the load balancer more accurately than with normal load-balancing metrics.

Other noteworthy features, such as optional server-side agents and configuration synchronization capability, make Hydra5000 a contender. However, the absence of a remote-management utility and the need for a monitor and keyboard don't score points. And while we were pleased with the configuration process and maintenance of the Hydra5000, we found the nomenclature and configuration tools to be more confusing than those of BIG/ip³, Resonate, ServerIron and LocalDirector.

F5 Labs BIG/ip³ 1.8
Similar to the Hydra5000 in appearance and internal workings, the hardware load balancer BIG/ip³ also shares some of its look-alike's inadequacies. Blazing performance is its strength, but the only management or real-time monitoring utility it delivers is a command-line monitor tool, inadequate in light of competitors' offerings. And while redundancy was easier to set up and configure with BIG/ip³ than it was with the Hydra5000, BIG/ip³ is limited by its serial connections. It addressed security during configuration using the SSH (Secure Shell) telnet tool F-Secure.

As with Hydra5000, BIG/ip³ requires a monitor and keyboard for initial configuration. After we got the unit up and running, configuring the Web cluster was as easy as it gets. Using BIGPIPE, a command-line configuration tool, you can create and bind together real and virtual servers in any combination to form Web clusters. With the Web cluster configured and operational, we used BIGSTAT to monitor the traffic statistics. While this worked fine for general information, it was much more limited than the real-time monitoring features of WSD Pro and Resonate Central Dispatch.