Scan found no incidents when expected

Products

• Data Loss Prevention Core Package
• Data Loss Prevention Endpoint Discover
• Data Loss Prevention Network Discover
• Data Loss Prevention Discover Suite

Issue/Introduction

A periodically run scan against about 15,000 workstations normally yields roughly 200,000 incidents. Newest scan got zero incidents. 

Cause

Error message in logs:

Got file system IO exception for file "null": /var/SymantecDLP/DetectionServer/16.0.00000/../../ServerPlatformCommon/16.0.00000/index/DataSource.1.2.2471.rdx.0.tmp (No space left on device)!

Resolution

Detection server is running out of disk space.