1. Self-Monitoring, Analysis and Reporting Technology System (S.M.A.R.T.)
2. Reference
   1. http://en.wikipedia.org/wiki/Hard_disk_failure
   2. Defect defination http://www.pcmag.com/encyclopedia_term/0,2542,t=hard+disk+defect+management&i=55545,00.asp
   3. Plist and Glist http://raidsjhf0.blog.163.com/blog/static/117425028200978114128275/
   4. http://smartmontools.sourceforge.net/badblockhowto.html
   5. Google research paper
      1. Failure Trends in a Large Disk Drive Population.pdf