"Pre-fail" is the type of SMART attribute. Seeing "pre-fail" in the column does NOT mean the drive is failing. There are two types, pre-fail (denoting a value outside threshold would indicate a failing disk) and old-age (denoting a value outside threshold would indicate a very old disk). I've hit old-age many times on servers, but I've only hit pre-fail on one disk. Though SMART is a good utility to have, it won't detect all failures. Also, I personally use SMARTReporter ( at http://www.corecode.at/smartreporter/index.html ) on my Mac. It works great, it's free under the MIT license, and it is unobtrusive. Hope this helps.