1. The loss of VDB cache will result in the wrong render result.
2. The Vray 3.20 version and later has added new particle cache interface Vray Volume Grid, supports OpenVDB (.vdb), Field3D (.F3d) or PhoenixFD (.aur) file types.
3. In 3ds Max, the default name is VRayVolumeGrid ***. The cache path must use the E-Z disk drive path, such as E:\project\files\... instead of the IP path (\\192.168.1.1), the network share path (\\share\files\projects), C disk drive path (C:\files\project) or D disk drive path (D:\files\project).