IHS/Websphere 6.1.31 on AIX - Heavy Load - Stop accepting request afet 170 concurrent users - Connection Refused on same server

I was wondering if someone could point me out into the right direction. Right now our IHS / Websphere Server is unable to handle more than 170 concurrent users.

We have tuned the IHS, Websphere Thread Pools, Datasource properties, JVM H开发者_开发问答eap and kernel parameters.

On heavy load we are seeing this in the IHS plugin log

[Mon Jun 27 10:42:15 2011] 00e90070 00002f30 - ERROR: ws_common: websphereGetStream: Failed to connect to app server on host 'XXXXXX', OS err=79
[Mon Jun 27 10:42:15 2011] 00e90070 00002f30 - ERROR: ws_common: websphereExecute: Failed to create the stream
[Mon Jun 27 10:42:15 2011] 00e90070 00002f30 - ERROR: ws_common: websphereHandleRequest: Failed to execute the transaction to 'XXXXXXNode01_YYYYYY'on host 'XXXXXX'; will try another one

Error 79 is connection refused! The strange thing is that both the IHS and the Websphere are on the same server...

Verifying the Thread Pools in the WAS we don't see them reaching their maximum. Monitoring the HEAP it seems OK...

Any ideas?

What is the number of maximum concurrent connections specified @ the Web Containers in WAS Cluster?

Can you make a direct call to the XXXXXXNode01_YYYYYY (by passing the IHS) when this error occurs via your browser)? If it still gives your errors, it simply validates the message provided by the plug-in.

HTH

Manglu