gtuhl: startup IT and software development

At work we have been pulling various infrastructure tasks into development sprints to prep for some larger clients in the near future. I snagged the task of researching and setting up load balancing equipment and want to share the experience. Perhaps my google searching abilities are just not strong enough, but I had real difficulty finding current, meaningfully deep discussion or comparison about the hardware load balancing products available. I did find Load Balancing Digest to be pretty helpful for general information and introduction. This post is just a record of my relatively shallow and unqualified experience. I would really love to hear any comments, feedback, or opinions.

Options

In my searching I encountered a pretty clean separation of product categories. There are devices that cost less than $5k each and then devices that cost more than $10k. From my limited research it seems the 5-figure devices were presented as “appliances” and “platforms” that were full of features I really didn’t need. I just wanted a load balancer not a firewall + router + load balancer + ssl accelerator + whatever else all in one package. We also don’t anticipate needing the connection counts and throughput abilities of some of these more expensive products for a long while so the sub $5k market suited our situation just fine.

I spent some time looking at the following vendor’s spec sheets:

LoadBalancer.org
Coyote Point
Barracuda
CAI Networks

The fact that all of the various spec sheets offered different fields combined with my inability to find very much meaningful discussion/comparison online caused by decision to be weighted heavily by the small pieces of information I did find. The CAI Networks WebMux products were spoken highly of in several forums, their low end device had specs more than satisfying our requirements, they support replicated pairs, and they had more capable products should we need to upgrade in the future. So I contacted AVANU, one of the resellers listed on the CAI Networks website, and had an evaluation unit of the WebMux 481S shipped over free of charge. It arrived in 3 days.

Setup

Once we got it in the office I was able to set it up in 20 - 30 minutes. The documentation is reasonable and it is based on Linux Virtual Server (as are many of the load balancing products out there) so the documentation for that project can be consulted for details that the Webmux documentation leaves out about scheduling methods or terminology.

I went with the Out-of-Path Mode configuration described in the manual and we did layer 4 least connections persistent scheduling. Our servers kept their existing IPs and all clients are sent to the farm IP setup in the WebMux. The manual suggests adding a loopback to the machines involved in your cluster using iptables but I instead setup a loopback alias with # /sbin/ifconfig lo:1 [farm IP] netmask 255.255.255.255 up.

So literally the complete configuration involved only the following:

• Power up the WebMux and connect its server LAN port to our switch
• Follow the Common Configuration instructions in the manual for initial setup
• Use the web configuration panel to add a farm and assign it an IP
• Use the same panel to add the servers to the farm
• Login to each server and setup the loopback alias to the farm IP
• Done

We have not yet taken the step of using the JBoss Cluster capabilities so on the software end configuration was straight forward. The WebMux supports multiple farms as well so you could use the same device to cluster other services (SMTP, DB) behind the web servers.

After setup I fired up JBoss on all of the involved servers, used a load testing tool (WebLoad) to send a ton of fake users to the farm IP and watched the WebMux web panel to verify connections were appearing evenly across the machines. Everything worked perfectly.

Of course all of this was done in our development environment. Once I have actual experience with the machines in production maybe I’ll post again with more informative content.