You need to move the incremental_index directory on your Network Discover Server to a different drive or folder.
DLP Release: 15.x, 16.x
To relocate the incremental_index directory, follow these steps:
1. Stop the Symantec DLP Detection Server Service on the detection server.
2. Move the incremental_index directory to your desired location.
3. Grant full read-write permissions to the DLP user for the new location.
4. Edit the configuration file:
# directory for the incremental scanning indexes
com.vontu.incremental.index.dir = DRIVE:/ProgramData/Symantec/DataLossPrevention/DetectionServer/15.8.00000/scan/incremental_index
5. Start the SymantecDLPDetectionServerService