dump area

Hello every one
am using oracle 11g on win2003.
i have warning on the OEM : "96% of background dump area is used".

What is the init param controlling the size on the dump area?
How can i delete the trace files using OEM or SQLPLUS. (i dont want to
delete them manually)

thank you.

why dont you want to delete them manually? just set up a scheduled job to do it

With OEM you can schedule an OS job to "clean-up" those areas. ;)