Joseph, Joel, out of curiosity, is there any chance are you using EXTERNAL
library types?

I know TSM will dismount an idle volume if it needs a mountpoint in 3494's
as Kent has pointed out.  I think it may behave the same way with a SCSI
library type also.

In fact, on a hunch, I just now checked my TSM 3.7 Admin Guide, Appendix A,
External Media Management Interface Description.  The valid return codes for
a Volume Mount Request are:
    SUCCESS
    DRIVE_ERROR
    LIBRARY_ERROR
    VOLUME_UNKNOWN
    VOLUME_UNAVAILABLE
    CANCELLED
    TIMED_OUT
    INTERNAL_ERROR
There is nothing that indicates waiting for a mount point.  That could
account for idle volumes not being dismounted; TSM doesn't know that the
External Library Manager is waiting for a mount point.

Alex Paschal
Storage Administrator
Freightliner, LLC
(503) 745-6850 phone/vmail