vmdareq -a can be important to use, as it will display drive reservations. Depending on your rev level, NBU can leave bogus drive reservations when jobs end, tapes dismount & drives should release - but don't. This happens worst in a mixed Windows/UNIX environment + SSO. We use vmdareq to check for bogus reservations at least once a day.
vmdareq -a will also display scan-host assignment of media servers in SSO. The importance of scan-host assignement varies, depending on what level Veritas employee you talk to, but our experience tells us that if it is not right, you're gonna have problems.