The NeuShield overlay is always stored on the same volume as the protected data. For example, if most of the protected data is located on the C:\ drive, then most of the disk space used by NeuShield will also be on the C:\ drive. It is not possible to store the overlay for one volume on a different volume. If you have extra space on a different volume, it is recommended that you either move the data you want to protect to that volume or only protect data on that volume. The recommended configuration for NeuShield typically requires an additional 10% disk space based on how much data is being protected on that volume.