Please look for any core files generated under $INFA_HOME/server/bin which may have build up and use disk space.
Review as well any sessions which may have failed at the same time: maybe temporary file for the run are not deleted: check session logs for full path.
Thanks & Regards,
This is a question to discuss with your network administrator / Linux administrator. The only exception is what Segolene has pointed out: temporary files ($PMTempDir\, $PMCacheDir}) may fill up the file system to naught, and core dumps in .../server/bin may block much disk space as well.
Other than that that's one typical task of system monitoring, not of Informatica software. The Informatica platform is (in terms of disk space usage) nothing but an application, so thorough and constant system monitoring is in order here.