I think you're talking about what's being referred to as "LAN-free" backups
where the metadata is transmitted over a control path (LAN if you like)
while the data itself could be transmitted over an alternative, possibly
dedicated storage network.  In this scenario you would be able to use any
available network-attached tape drive to perform your backup.  This
would/could include a locally attached tape drive that was defined to ADSM.

At Planet Tivoli in May, Tivoli did announce plans to enable this type of
feature in ADSM but I don't think it will make the next release (Sept.?).  I
think we're looking at next year.  Tivoli may want to comment on this.

We have enabled ADSM to use network attached tape drives through our
middleware and the ELM feature of ADSM server.  The result is more efficient
use of your tape investment.  One ADSM server can access drives attached to
other hosts or contained in libraries across the network.  Conversely,
multiple ADSM servers can share drives in a single library (not a native
feature).

Increasingly our clients are using fibre channel as their topology of choice
in constructing the dedicated storage network for it's high bandwidth and
support of both SCSI and IP protocols.  If you would like to hear more,
contact me offline.

Regards,

Keith Nelson                 Voice: 612.865.4631
Gresham Enterprise Storage   Fax:   612.925.3570
knelson AT openmic DOT com          Web:   http://www.gresham-computing.com