JBoss AS7 does not need the database 'DefaultDS' as before, in previous versions JBossMessaging and EJB-Timer store data into this scheme.
AS7 use HornetQ which use filesystem persistence. Also the ejb-timer persistence has a filesystem persistence.
As you mentionend, you don't have to change any configuration if you remove the DefaultDS configuration.
Your MySQL is only used if you deploy an application.
To Wolf-Dieter Fink
Thanks for your explain. It's very clearly and make me to know why.
I'm a rookie at Jboss and Java, and I'll keep learning.
Thanks for your help again.