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wtwagon_99154
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Feb 10, 2010

Health Check Issues

The Scenario:

 

 

We are performing some load testing of an application and are using a health check as follows:

 

 

GET /blah/blah.asmx HTTP/1.1\r\nUser-Agent:Mozilla\r\nhost:blahblah.blah.net\r\n

 

 

We look for a 200 OK

 

 

Monitor interval: 5 seconds

 

Timeout: 16 seconds

 

 

We have 2 servers in the pool and they are all green at the moment.

 

 

The Problem:

 

 

As soon as we start throwing LoadRunner load tests at this VIP, all the servers go to red almost immediately(we are throwing a small amount of load, around 40 concurrent sessions). What really gets me is that I can run the same exact request as above during the load test and I am able to successfully get there and receive a 200 OK.

 

 

I also tried swapping the interval to 15 seconds with a timeout of 46 seconds and received the same problem (although this time, it happened after 5 minutes instead of almost immediately).

 

 

What steps can be taken to try to diagnose why the F5 is thinking these nodes are down, when they are clearly not?

 

 

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