Because V-Ray 6 heavily integrates assets into the Chaos Cosmos Browser, you can pre-cache materials while online to preserve them for full offline availability later.
The default installation paths for the material library are:
For access to Chaos Cosmos materials and assets, use the Cosmos Browser approach:
Which you use (3ds Max, SketchUp, Cinema 4D, etc.)?
For some versions (like Maya), you can run the mtllib tool found in: C:\Program Files\Chaos Group\V-Ray\Maya 20XX\maya_vray\bin . 3. Configuring Offline Access in Cosmos Browser