The /tmp folder is filling up with kvxxxxxx files on Discover server.
DLP 15.x
This process is working as designed. While the scan is running the server will require large amounts of space. More space is typically needed for an incremental scan than a full scan.
Once the scan is complete these file(s) should automatically be removed.
(Optional) At times it may be necessary / desired to define a different location for the temporary files. To do this browse to the server settings under the server / detector page then specify the alternate location under the FileReader.TempDirectory setting.
You could have a cron job or task that can then purge the content of this folder (files older than 24 hours).