You can use vi -b for binary editing on unix (install vim if your standard vi doesn't support it). just don't add nor delete anything, overwrite with "R" command. I'd test few different not-so-trivial scenarios like messing up a rollback segment header, a rollback segment block, some current online redo block etc. tanel. _____ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of LS Cheng Sent: Saturday, September 02, 2006 23:58 To: Charles Schultz Cc: Oracle-L Freelists Subject: Re: How does one manually corrupt a database (database file, redo logs and backups) have you tried with an hex editor?