maybe this will help, maybe not.
I have windows xp and have netbeans 7.1 with glassfish 3.1.1 installed.
under netbeans I ran a web app MyWebApp with javaee (entity beans) and placed info in a database "sample". It appears to be
created at C:\Documents and Settings\David\.netbeans-derby\ in the form of a folder named "sample".
Whenever I use netbeans, the glassfish server and the database are started and when I stop netbeans the glassfish server and the database turn off.
I then must copy the folder to %DERBY_HOME%\bin !! when the database is OFF !!
Then with asadmin.bat start-domain and asadmin.bat start-database get the show running again.
Then with the browser and http://localhost:8080/MyWebApp
I can look at the database.
But !! don't forget, netbeans puts the database in C:\Documents and Settings\David\.netbeans-derby\ [for some strange reason]
and when using glassfish server like a normal human, without netbeans, the database must be in %DERBY_HOME%\bin [for yet another strange reason]
hope that helps