Create free-space thresholds on data segments as well as on log segments.
For example, you might create a free-space threshold on the default segment used to store tables and indexes. You would also create an associated stored procedure to print messages in your error log when space on the default segment falls below this threshold. If you monitor the error log for these messages, you can add space to the database device before your users encounter problems.
sp_addthreshold mydb, "default", 200, space_dataseg