Hi Bill,
BackupExec using the Archive Bit to see if the data has been change or not.
TSM verify multiple values with the TSM Database (If you want to find out more, 
then configure Journal Backup on one of your test machines. Then will you see 
all values).

But a good explanation why BackupExec backup less then TSM is probably that the 
customer has another software that also working with the Archive  Bit and reset 
the value time to time. 
That mean when BackupExec runs. It maybe don't backup all files that has been 
change the last 24h, so the customer may not have a complete backup.

I know for an example, CBMR will remove the Archive bit as default, that can be 
a reason why BackupExec backup less.
Ask the customer to verify that non other software are removing the archive bit 
from the files.

Best Regards
Christian Svensson

Cell: +46-70-325 1577
E-mail: Christian.Svensson AT cristie DOT se
Skype: cristie.christian.svensson
Supported Platform for CPU2TSM:: 
http://www.cristie.se/cpu2tsm-supported-platforms


Is there a list of what the TSM client checks for on a file to determine if
the file needs to be backed up? I have a client that is running both
BackupExec and TSM on servers and he's telling me that TSM backs up way more
than backupExec and 'what the users have changes.' Using their words.

This customer also has TPC Data and is using the Files as Risk report to
estimate how much data needs to be backed up. But I think that just goes on
the archive bit and the last modification date/time of the files. Which is
only a fraction of what TSM uses to determine a file's eligibility for
backup.

TIA,
Bill Boyer