Physical Library/Tape drives are not possible on VM Machines. You can configure VTL, but to be honest, if you have disk space for VTL, configure it as Disk Based Storage Units.
I know it's not vSphere ESXi...
...but on my test rig - I can route/map/present (but not share) a SAS attached LTO5 to a VM...
e.g. Virtual Host - Windows 2008 R2 - VMware Workstation 10.0.3 - with SAS attached stanadlone LTO5...
...to either guest VMs of Windows 2008 R2 or RHEL 6.4 - and they can each see and use the tape drive - and use NetBackup without any issues - but not sharing - only one 'server' can have the tape drive at any one time, i.e. either the physical host or one of the VMs.
@NBU2010 - my advice is not to try it in production. It is not supported. And you don't want to risk your employer's data.
My use of VMware Workstation is not a true bare-metal hypervisor. I really would not look at this for production. It's not supported. If you loose data or run in to issues, neither Symantec nor VMware Support will be under any obligation to assist you. I wouldn't waste time on trying to get this to work. And Marianne has said that it has been proven to NOT work - so why even try?
Yes, it is possible to 'make it work' but, it is not supported by VMWare / Hyper-V or Veritas.
Therefore, the officaly answer is that it cannot be done as it is unsupported.
Consider that someone did this in a production enviroment, that hit some issues on a critcal restore with only one copy on tape ...
Here is the official Veritas doc:
Statement of Support for NetBackup 7.x and 8.x in a Virtual Environment
There is a list of virtual environments that do support tape - see page 7. Hyper-V and VMware are not part of this list.
Here is an example of someone who tried - everything seemed fine, but then started to get errors. Especially with tape positioning.
Only after 2 weeks did we find out that the tape library was configured on a virtual server.
I am locking this discussion as the original query was solved.