Suggest if you are not the System Administrator, you get that person's help - unless this is a test system that doesn't matter if it gets messed up - then have fun learning.
Otherwise, here is a link that may help you from
SunSolve
Normally (well, more to my experience), Oracle databases are set up with a volume manager of some sort. You state that
Quote:
they are not visible with the df command. I guess this means that their partitions have not been assigned to a file system.
A database can use a raw device - you would have to check that any database running on the system is not using it OR insure it isn't being used by swap (which may not show in a df command)