I was redeploying JBoss on to a new server today. It was already configured so i didn't think i would have any issues when starting. However i quickly saw many java.io.Exceptions in the server log.
After a quick bit of research I discovered that the user I created to run JBoss, (webadmin) needed an increase in the maximum number of files that it could have open in the system at one time.
If using Cent OS 6.2 do so by editing the limits.conf file in the /etc/security folder. ( you will need to be root ).
Below is a screenshot of where i increased the limit to 200000 for webadmin.
After logging out and logging back in as webadmin. the command # ulimit -Hn reported 200000 as the new limit on file descriptors.
After this i started JBoss and it worked like a charm.