What Happens If 6400 Pushed Beyond Its Capacity?

Deon,

 

 

In v10.0+, the TMM does not run on just one CPU, it grabs both just like it does for the other platforms. This means that TMM can consume up to 90% of both CPUs rather than 100% of one. This results in a nice performance boost in most regards (see SOL9763: http://support.f5.com/kb/en-us/solutions/public/9000/700/sol9763.html?sr=13375974). However it also means that tasks that were previously relegated to the second CPU will receive much less CPU time than before.

 

 

As for what the effect will be, I expect traffic will slow radically, probably to the point of some browsers timing out (and certainly some users). If CPU is actually maxed out you will also see TMM unable to respond to connection requests. It won't result in connection rejections by default, but connections that don't use ASM will timeout as well. Further, health checks will start to fail because the health check daemon, bigd, doesn't get enough CPU time to send health checks or process the replies. That will drastically decrease user experience because even connections that weren't timing out will be interrupted as the node they are connected to is marked down. Limiting TMM to only 90% helps this situation a lot, but under extreme pressure it will still happen.

 

 

Hope this helps.

 

 

 

--jesse