Background or ad-hoc jobs for risk analysis generate spool and log file. Unlike ABAP, where you can set reports to clean up job logs and spool files, GRC does not have house-keeping jobs available. You will have to write your own OS scripts to cleanup old logs from the file system.
The background job spool files are written to /usr/sap/<SID>/>INST>/j2ee/cluster/server0/virsa/bgJobSpool with name jobid.X.0 and the foreground tasks (with huge object selection) write _tmp.xx.x.0 at the same location.
If the file system fills up, the J2EE engine will hang. You need to restart J2EE engine after a disk full situation.