Load Balancing Digest

You’re stumped. There’s a problem with your infrastructure, and you’re not positive what it is. You checked a few things out, but the symptoms befuddle you. You’re pretty sure it’s not the load balancer, but everyone is pointing at you, and you’ve got no proof.
What do you do?
I’ve been in that situation [...]

One issue that trips up people when diagnosing load balancer problems is they see a connection has been made to a virtual service, so it looks like they’re getting through to the real server.
That’s not always the case. Depending on how your load balancer is configured, it could simply mean you’ve made a connection [...]

I mentioned I used telnet quite a bit a few posts ago. I don’t use it to log into anything (plain-text passwords over the wire anyone?), instead I use it as a basic TCP connection utility. I see if I can establish a TCP connection, and then I might throw a “GET /” [...]

As seen on Slashdot, a Microsoft tech blog outlines their hosting environment for microsoft.com. One of the interesting items that came up was that until a year or so ago, they were using NLB (Network Load Balancing), the no-frills Windows server Layer 4 load balancing that is included with the OS. Since [...]

When I’m diagnosing load balancing issues, there are three really critical tools I use:

TCPDump
HTTP Header dump (such as Live HTTP Headers)
Telnet

Yup, telnet. I don’t know about anyone else, but I use telnet excessively. Basically, I use it to test TCP connectivity, and with a quick “GET /”, to test to see if the [...]