Lets say the tape is empty (or you overwrite it) on 1st Jan but that job does not fill the tape, then you have 10 weeks to be allowed to use the remaining space on the tape.
If you don't use the tape again in the ten weeks then the 2 year overwrite protection starts at the END of that job (note: It is the end and NOT the bgeinning, which means it could be 2 years and a few hours from first use that the tape becomes overwriteable again, meaning a yearly repeating job won't be able to use it based on just 2 years). Also any space ioon that tape will become unusable on 10 weeks.
if you fill that tape on 5 weeks then the 2 year overwrite protection will start at the point the tape filled. (so not on 1st Jan any longer, but over a month later) - of course in this scenario there will be no space left on the tape.
If you continue appending data to the tape during the 10 weeks and it does not fill it, then the two year period will start just after the last job (probably the one that ran 9 weeks and 6 days after the first use.) If that happens then again any unused space becomes unusable.
However do yourself a big favour and consider upgrading all the obsolete operating systems, hardware and our backup software,as if you are running Backup Exec 9.1 you can't possibly be on any current products and could be much more prone to failure AND massively open to any security vulnerabilities. You also cannot expect assistance from us or people like Microsoft if you are on really obsolste technology. Basically how much would complete loss of environment and data cost you or your company - if it is more than the costs of updating your systems then action is needed.
