I need help understanding how the incremental backup works in TSM.

 

We have a TSM 5.1 environment. We have a 600gb folder on NTFS that has
just had its timestamp changed. Now

TSM looks like it's backing up all 500GB worth of files again, even
though the timestamp on the files has not changed.

 

My Question is. How does the timestamp on the directory effect TSM
baclient and secondly how do I prevent TSM from

Backing up all the files again?

 

Thanks in advance.