>      I have several mail systems, each having approx. 4 million files. On
>      an average day approximately 10-20% of the files change, so I am
>      looking at incrementals that will backup approx. 400,000 - 800,000
>      files each day.
>
>      ...

Just another thought on this: When doing an incremental backup, the first
thing the client has to do is to determine, which files have to be backed
up. This is normally done in the following way: the ADSM-server sends a list
of all backups it has, and the client compares this list with the actual
situation in the file system. Having 4 million files, this procedure
will take a lot of time and need a lot of resources.

You might consider using the "INCRBYDATE" option of the incremental backup,
which reduces the time spent in this first step. In this case, the ADSM
server is only asked for the date and time of the last incremental backup.
You should nevertheless periodically perform full incremental backups
(perhaps on weekends).

Reinhard Mersch                     Westfaelische Wilhelms-Universitaet
Universitaetsrechenzentrum, Einsteinstrasse 60, 48149 Muenster, Germany
E-Mail: mersch AT uni-muenster DOT de                   Phone: +49(251)83-2488