Hi, I have been performance tuning jboss, and have came across an issue related to DataSources. Each time I run a 500 user test, the application "pauses" for 200 seconds or so(no responses are seen). I have tracked this down to two separate issues, the first was with the number of Open file descriptors. I am using RHEL3, and this is set to 1024, for an indiviual process. I have moved this to 2048, on the grounds that each user connection(we are connecting directly to jboss), consumes one connection, and logically since everything in linux is a file, needs one file descriptor. I no longer get the "Too many open files"(note I have checked for increasing numbers of open files, but do not see this increasing over time), effectively I have an application that requires a lot of open file descriptors. Now this is stabalised. However, I still get the problem with "No managed connections available". I have changed all the relevant DataSource maximum connections from a default of 20, to a new default maximum of 200(changed in the ds.xml for each datasource). I have monitored the application and am getting around 100 data source connections maximum, per data source(ie I should have another 100 "spare"). However, I still have the error that there are no managed connections available. Can anyone shed any light on what options I might try next to track this down? I have included a stack trace from the log file..... Caused by: org.jboss.util.NestedSQLException: No ManagedConnections available within configured blocking timeout ( 30000 [ms] ); - neste d throwable: (javax.resource.ResourceException: No ManagedConnections available within configured blocking timeout ( 30000 [ms] )) at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:94) at org.jboss.ejb.txtimer.GeneralPurposeDatabasePersistencePlugin.insertTimer(GeneralPurposeDatabasePersistencePlugin.java:172) at org.jboss.ejb.txtimer.DatabasePersistencePolicy.insertTimer(DatabasePersistencePolicy.java:122) ... 100 more Caused by: javax.resource.ResourceException: No ManagedConnections available within configured blocking timeout ( 30000 [ms] ) at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.getConnection(InternalManagedConnectionPool.java:266) at org.jboss.resource.connectionmanager.JBossManagedConnectionPool$BasePool.getConnection(JBossManagedConnectionPool.java:454) at org.jboss.resource.connectionmanager.BaseConnectionManager2.getManagedConnection(BaseConnectionManager2.java:324) at org.jboss.resource.connectionmanager.TxConnectionManager.getManagedConnection(TxConnectionManager.java:301) at org.jboss.resource.connectionmanager.BaseConnectionManager2.allocateConnection(BaseConnectionManager2.java:379) at org.jboss.resource.connectionmanager.BaseConnectionManager2$ConnectionManagerProxy.allocateConnection(BaseConnectionManager2. java:812) at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:88) ... 102 more View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4052011#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...