Google’s study looked at more than one hundred thousand disk drives which were a combination of serial and parallel ATA consumer-grade hard disk drives, ranging in speed from 5400 to 7200 rpm, and in size from 80 to 400 GB. The observed range of annualized failure rates varied from 1.7 percent, for drives that were in their first year of operation, to over 8.6 percent, observed in their third year.
I have spent many sleepless waiting for a hard drive to fail simply because S.M.A.R.T. predicting impending failure. For several years I would have the following email message sent by cPanel.
Subject: [cPanel smartcheck] Possible Hard Drive Failure Soon
S.M.A.R.T Errors on /dev/hda
From Command: /usr/sbin/smartctl -q errorsonly -H -l selftest -l error /dev/hda
ATA Error Count: 1
Error 1 occurred at disk power-on lifetime: 93 hours
—-END /dev/hda–
I eventually switched to another machine simply because I couldn’t take the stress but the hard drive never did fail.
Take a look at Google’s findings…if only I had known! 
