VFB Preset File

[eosek]

What is this: VFB Preset File?
Where does it come from?
How to prepare this file hotel.vccglb?

[bdancer]

eosek, this parameter is empty by default, I'm not sure why it's set to hotel.vccglb in your scene.
You could create such presets in the VFB: open the corrections rollouts, make some corrections then press "Globals..." -> "Save", then choose this file in the "VFB Preset File".

[eosek]

That is, is it only saving settings with Globals?

[andybot_cg]

It's connected to the V-Ray Frame Buffer, not Blender settings. Blender just tells V-Ray to load that file in the VFB at render time.

[eosek]

How to set it up? to example to get a sharp image?

[andybot_cg]

That's not what it does. That just makes VFB adjustments (exposure, contrast, curves, etc.) For a sharper image, decrease the noise threshold in your sampler settings.