I'm using the "Disks" program in Ubuntu 14.04 (live DVD) to assess the health of a drive I suspect is failing. However, when I first opened the program, it showed that the overall health was OK and all assessments are OK as well. I then tried to run a short self-test, but now the overall assessment shows a red "SELF-TEST FAILED". In the details section it says "Last self-test failed (read)" and "threshold not exceeded". All individual assessments are still OK though!! What I don't understand is, does that mean that the test executed and determined that the drive is a goner, or does it mean that the test didn't actually execute properly?