F5 balances blade loads

A blade system without a load balancer would be like Chicago’s O’Hare without air traffic control. One of the core applications for server blades is to serve as the front end to Web hosting, firewalls, VPN servers, SSL accelerators, Java application servers, caches, and other transaction systems — in other words, applications that lend themselves to horizontal scalability, where the way to increase performance of a system is to add more servers, each performing a share of the workload. Traffic managers, such as F5 Networks’ Big-IP Blade Controller 4.2.2, serve a vital role in such cases, as they dynamically distribute the workload between those identical servers.

The F5’s Big-IP Blade Controller software, which installs directly onto one of the blades in a rack, is designed to be an integral piece of the blade ecosystem. It acts as an application-level counterpart to hardware administrative tools, such as RLX’s Control Tower, providing a robust and dynamic set of functions for load balancing and security. We tried Blade Controller 4.2.2 on one of our RLX blades and found that F5 has done a solid job creating the blade-server implementation of the Big-IP software.

In addition to its Big-IP load-balancing appliances, F5 sells versions of the Big-IP software for server blades customized not only for RLX’s system, but also for Dell’s PowerEdge 1655MC, HP’s ProLiant BL10e and BL20p, and Fujitsu’s Primergy BX300. The RLX version of the software costs $3,500 for the server, plus $400 per managed blade.

After installing the Blade Controller image on our RLX blade (not a trivial task, but not normally part of the customer experience), the software was easy to configure through its browser interface, which leads the administrator through configuring VLANs for sets of load-balanced machines and publicly accessible IP addresses and ports for accessible services. F5 builds a great deal of security into the system, which would make it difficult for hackers to bypass the load balancer and access the individual servers directly. Blade Controller’s stateful fail-over capabilities also ensure that transactions aren’t lost if a balanced server dies — a feature that worked quite well in our testing.

There are both benefits and drawbacks to integrating the Big-IP software (or any load balancer) onto the blades. On the benefit side, the load-balancing server’s hardware would be physically administered as part of the blade’s management scheme (in the case of RLX, the Control Tower applications). However, because F5 uses its own browser-based console, you can’t actually control the functioning of the load balancer from within RLX’s physical administration package.

Another benefit is that F5’s load-balancing software can be purchased pre-installed from the blade server vendor, providing one-stop shopping and one-number tech support. And of course, if the load balancer is on a blade, it won’t take up too much real estate in the rack. Plus, a blade implementation is a lot less expensive than buying a dedicated appliance.

On the down side, there’s no denying that the individual servers within a blade system lack the performance and reliability features that stand-alone servers offer. In the case of RLX, the server supported by F5 is the 800MHz Transmeta Crusoe-based ServerBlade 800, with non-hot-swappable drives. Compare that to the numerous and affordable dual Intel Xeon-based servers on the market that offer high-speed and high-availability power, cooling, and storage, as well as an option for Gigabit Ethernet that today’s blade servers generally lack.

Given the critical role that a load balancer plays in a server farm, our opinion is that this function belongs on F5’s high-availability server appliances, which are tuned specifically for load balancing. Some of the appliances even contain ASICs for packet acceleration, which the Blade Controller software lacks(see ” Doing Data Detail “). Now if F5 would work with the blade server manufacturers to create customized hardware, rather than merely a software preload, it would be the best of all worlds.