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How to predict a hard drive's death

Posted: 17 Nov 2014 ?? ?Print Version ?Bookmark and Share

Keywords:SMART? hard drive? 187?

Since the concept of SMART (Self-Monitoring, Analysis and Reporting Technology) came to consumer hard drives about a decade ago, users have been mostly unsatisfied with it. The technology has rarely accomplished its purpose, which is to tell if the device is about to die.

The problem lies in its delivery of tons of data, which are mostly useless, as well as inconsistent statistics among hard drive manufacturers, ExtremeTech reported. SMART fails to tell the user whether his/her device will soon expire. What it does instead is provide different variables that vary from drive to drive, while the user is left to guess if the storage tool is healthy or not.

There is another downside. Although SMART returns myriad information, some of these are actually useful. However, these data are obscured by the inconsistency among drive makers, who also never point the users to important attribute and variables.

In order to solve this, people at Backblaze found a way to predict the death of hard drives with the use of SMART.

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Backblaze analysed SMART data in the past couple of years from around 40,000 hard drives, which were developed by makers such as Seagate, Western Digital, Hitachi and HGST. What it did was to work backwards, reviewing the reported SMART data from the failed drives from the preceding weeks and months. After examining the records, Backblaze pinpointed five SMART attributes that it thought were the indicative signs of a drive's expiration.

The five SMART metrics that signal the impending disc drive failure are:

  1. SMART ID 5 (0x05): Relocated Sectors Count
  2. SMART ID 187 (0xBB): Reported Uncorrectable Errors
  3. SMART ID 188 (0xBC): Command Timeout
  4. SMART ID 197 (0xC5): Current Pending Sector Count
  5. SMART ID 198 (0xC6): Uncorrectable Sector Count

This is how it works. A hard drive is still healthy if it shows none or a count of zero for all of these mentioned stats. On the other hand, if one or more of these metrics has a value of one or up, chances are high that the drive will soon be out of use. Therefore, users must already back their data up immediately.

Backblaze also mentions that SMART ID 187 (0xBB), Reported Uncorrectable Errors, is one to look out for since all makers have the same definition for this and the number is quite simple to take.

For a more detailed explanation, check out Backblaze's blog.

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