Application Delivery (ADX)

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New Contributor
Posts: 2
Registered: ‎08-19-2010

Remove real server from pool if app is flapping?

Hello there,

We have health checks enabled for a real server behind a ServerIron 4G. We have http requests forwarded to a web server that then proxies to our application.

What is happening is that one or more of the application threads behind the web server is hanging occasionally. This causes about half of the requests sent to that real server to be fail, and the other half succeed, which brings the real server up and down on the 4G.

Here are some example logs:

...

2010-08-10T00:00:49-07:00 <local7.notice> 10.33.0.5 lb01, L4 server 10.33.0.208 srv05 port 80 is up

2010-08-10T00:01:05-07:00 <local7.notice> 10.33.0.5 lb01, L4 server 10.33.0.208 srv05 port 80 is down due to healthcheck
2010-08-10T00:01:13-07:00 <local7.notice> 10.33.0.5 lb01, L4 server 10.33.0.208 srv05 port 80 is up
2010-08-10T00:01:30-07:00 <local7.notice> 10.33.0.5 lb01, L4 server 10.33.0.208 srv05 port 80 is down due to healthcheck
2010-08-10T00:01:38-07:00 <local7.notice> 10.33.0.5 lb01, L4 server 10.33.0.208 srv05 port 80 is up
...
To me, this is an example of a service flapping. Is there a way to tell the ServerIron4G to remove that real server from the pool if a port is flapping? I am aware of L7 health checks and settings like no-fast-bringup, though in this case I believe we would have the same result. The L7 health checks would pass, and then fail, and then pass again as they connected to different application listeners.
Additionally, we will continue to fine-tune our application and we have monitors in place to monitor to threads directly, but we still want the SLB to be smart about adding / removing servers from its pool.
Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: Remove real server from pool if app is flapping?

If i am reading the time stamps correctly then the events are then just minutes apart.  If that is so then I do not think you have any options within the ServerIron for that sorry as the time is way too far apart.

New Contributor
Posts: 2
Registered: ‎08-19-2010

Re: Remove real server from pool if app is flapping?

They are 10-20 seconds apart...

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