Tracking file storage space use

[Alan Dayley]

I have a server running Red Hat Enterprise Linux 5.  It's running very
well but lately we have been running out of disk space on occasion.
The truth is we need more storage and that solution is coming.  In the
mean time, I need to figure out where all the space is being consumed.

Every once in a while I can see 3-5GB get consumed in about a day.
Then, when I warn everyone we are running out, this space suddenly
comes free.  I think a user is eating the space and then freeing it up
when my warning goes out.  But none of the users will admit to this
behavior.  That's not a big deal because, whether a user or not, I'd
like to know what or who is eating this space and then releasing it.

The server is running SAMBA shares for /home and other directores,
Bugzilla with MySQL on the database, TWiki, Subversion, CVS and ftp
services.  Tracking each of these individually may be a bear.  I was
thinking there may be a tool that tracks recent usage from the file
system level.

What tools can I use to get a handle on this issue and increase my
knowledge about disk usage?

Alan