We use three servers to handle our job processing /server needs. One server is dedicated to creating vis files, one for syncing files to Buzzsaw via the job processor and the third is the actual Vault server. This arrangement allows jobs to be processed concurrently while keeping server tasks independent- one drawback, it does require an extra license to run the second job processor.
If you don't have need for Buzzsaw syncing, two servers would work just fine. One observation, I found that job processor errors are reduced on a non-virtual machine (ie one with a proper graphics card and monitor) When we had our jp on the virtual server it frequently experienced heidi driver errors.
Good luck,
Blake
