Zeus Load Balancer
Zeus Load Balancer is worth a look for simpler sites, the budget-conscious and/or companies with Unix-based hardware platforms.
Zeus Technology sells Zeus Load Balancer only in a mandatory failover configuration for $10,000. (In contrast, a second Web Server Director Pro must be purchased for failover protection.) The Zeus software can be installed on any two machines running a Unix-based operating system such as Linux, FreeBSD or Solaris.
The fault-tolerant pairs depend on Domain Name System servers to direct incoming clients to the traffic IP addresses, similar to the virtual IP addresses used in hardware balancers. In the event that one of the Zeus Load Balancers fails, the other box will automatically take over all of its partners traffic IP address and active connections.
The processor speed and amount of memory on the hardware directly affect Zeus Load Balancers performance. We installed Zeus Load Balancer on a pair of Compaq 450MHz Pentium II-based DeskPro computers with 512MB of memory and running RedHat Linux 7.0. Using the Flame- Thrower tool, Zeus Load Balancer turned in about 6,600 requests per second (approximately 3,300 requests per second per box).
Zeus Load Balancer has a much simpler load balancing scheme than Web Server Director Pros. Managed through a Web browser, Zeus Load Balancer uses a proprietary locality-aware request distribution algorithm; all traffic is load-balanced using this algorithm. Administrators can configure which protocol and ports to load-balance, and rules can be set up so specific requests can go to specific servers. For example, we were able to create a rule that directed all requests for GIF or JPEG files to certain Web servers.