Hey guys.

Thanks for your replies.

I have started the same thread in firebird-support (http://groups.yahoo.com/neo/groups/firebird-support/conversations/topics/123306) to address the firebird issues. The reason for this thread in firebird-php is simply if the error is in the ibase library or has something else to do with PHP.

Sorry for the missing information.

The servers hardware:

2x AMD 2.20 GHz

32GB Ram

64bit Windows server 2008 R2 Standard

The firebird DB size is 6.2gb.

The main issue (we think) is the database connections and not the queries. We have made an extensive work in optimizing the queries and havent registred any issues with the queries. When we restart the webcluster all transactions are closed and the transaction counter is at zero. When we start the cluster and the connections start to build up we see the problem begin at 400-500~ connections.

There are no errors in the system log nor in the firebird error log.

The firebird DB is running SuperClassic.

The config kan be found on pastebin http://pastebin.com/ZzxL4xVc

The webserver cluster is running apache2 prefork with to additionel loadbalancers in front with varnish and nginx running. We also have a cluster of memcache servers caching data for reuse and making sure that firebird is called as little as possible.