1. Installation
It is up to you where you will run your second TrueNas Scale instance, but it is recommended to either store it bare metal or as a VM with dedicated drives.
- You have a PBS machine
- You have a TrueNas scale machine VM or bare metal
- And a third machine
If you only have one extra machine and not enough drives to provide pass through to a PBS VM and TrueNas scale VM then I would recommend to run run TrueNas scale bare metal and install PBS as container on top of it. This does of course mean that you cannot create another PVE VM for other purposes on the backup instance. However, TrueNas Scale also offers containers, and vm's nowadays so you could still run some extra apps on the backup machine if you have the resources and would like to do that.