Kris,

        NetBackup does not know if VTL duplicates tapes out of the back.  This
presents a problem - you can only have a single copy of the tape.  Say NBU host
wrote to tape VLT000 on the virtual library and that tape got duplicated
through the back end to a physical LTO tape with label VTL000(has to be the
same) then once the duplication is done VTL will erase it's own tape copy and
only one on physical media will exist.  If you need to retain two copies of the
tape, one on-site the other off-site at the same time you will need to use NBU
duplication through either Vault or manually.

        Using same cards for disk and tape is definitely not recommended by any
vendor I know.  You can, potentially, avoid the issue of limited PCI slots by
using dual-port HBAs.

        As far as using NT 4.0 you will need to check with a specific VTL
vendor, they may or may not support it.