If your clients are doing unfettered incremental backups of file systems, then the following would yield a MB approximation, very quickly: SELECT SUM(CAPACITY*PCT_UTIL/100) FROM FILESPACES which is based upon TSM's information about the file system as gotten from the last client operation. By definition, the files on the client represent all the Active files in TSM storage where the activity is incremental backups.
Richard Sims