Implications of Google Study on Used EMC CLARiiON Hard Drive Industry

"The study was also able to find meaningful correlation between four SMART signals—all of which were indicative of bad sectors—and increased chance of failure over the study period. In used drives, it is a given that some of the drives vendors obtain for resale will have raised one of these four SMART signals. To account for this, great care is taken to test and classify drives before they are released back on the market. Typically, drives are given a grade; for example A, B and C. When a drive is found to have raised any of the four SMART signals Google researchers identified, they are given a grade of B or C, and priced accordingly. B drives may have some “soft” errors or specific types of re-allocation errors that allow for limited use in non-critical situations. C grade drives are often sold as parts or properly recycled. It is useful to note that only 56 percent of failed drives in the Google study raised such errors. Additionally, of the set that did raise those four signals,
http://www.tabdatasystems.com/implications-of-google-study-on-used-emc-clariion-hard-drive-industry/