DAS LTO Server connected to Veeam Backup Server on VM ?

Yes you can do this for sure with configuration backup and restore to the VM then take control of the server with tape as a tape server.

Yes, it is possible to do this.

The main point I would evaluate is the network path between the VBR and the Tape Server. The tape devices will remain physically connected to the Tape Server, but the data transfer will now also depend on the network connection between the VBR infrastructure and the Tape Server.

Basically, the data flow will change from:

Repository → FC/SAS → Tape

to:

Repository → Network → Tape Server → FC/SAS → Tape

Because of that, network bandwidth should be considered in the new design. Depending on the network interface speed, repository location and LTO generation, the network connection could become a bottleneck and impact the tape job throughput.

I would mainly validate the available bandwidth between the repository/VBR infrastructure and the Tape Server and compare it with the expected throughput of the LTO drive.

Thanks for your answers. I forgot to specify that the hypervisor is Hyper-V. All the manipulations have to be done on Veeam or is it necesary to add a configuration on the host/hypervisor ?

If i understood the server running B&R is also the hyperv-v host for the VM where you want to move B&R.
The important think to understand that in this config you have probably an all in one solution where the windows server act as B&R, repository (as defined by veeam) and tape server.
What you use as repository? a NAS? connect how? (SMB, NFS, ISCSI)?

Because the real traffic (and the performance issues) is that the traffic of backup go from the repository to the tape server, and the performance can be an issue with the tape drives, that required a CONSTANT MINIMUM stream of data, otherwise the drive will stall (it must stop the tape, rewind and restart, wearing the tape an tanking the performance).
And by repository it mean the Veeam component that execute the data move.

So if you move only the B&R component and the rest is the same you’ll be fine.

But in any case, to do an assessment, you need to explain in detail your architecture.