I've got a Sun Storage 7000 that I'd like to backup/restore via the built-in NDMP service, since we've got an secondary SAN attached which is available via two 10GbE links to the primary storage I'd like to deploy it as a VTL solution. The secondary storage could easily be expanded with a SCSI HBA connected to a (small) 28 slot library providing two LTO4 drives. It seems that currently no FOSS backup app is able to be used as a NDMP VTL (with copy to physical tape) solution. Any low cost solutions?
Have a look at ndmpjob. I have no direct experience with it but it looks like it does everything you'd want with NDMP.
And it's free, source included.