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  1. #1
    New Lounger
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    Dec 2009
    Perth, Australia
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    SMART Data not so smart?


    I have a small Computer Repair Business and as part of the service I do a free hardware test of every computer I get in.

    This has found things like memory faults, damaged sectors etc etc.

    What I also do is a SMART (Self-Monitoring, Analysis, and Reporting Technology) test. I use Crystal Disk Info and HDTune Professional.

    Many times a computer will pass the test for damaged sectors etc but then fail the Crystal Disk Smart test for things like Reallocated Sector Count and Uncorrectable Sector Count. If it fails with CDI then I test with HDTune and if it fails that, I then test using manufacturer specific tools e.g. Seatools for Seagate drives.

    90 percent of the time the drive will pass all the manufacturer tests so what I do then is tell the customer the hard drive is showing signs of wear and tear and could last anywhere from 5 days to 5 years it is impossible to tell. I then recommend they backup regularly just in case.

    I am doing wrong here? Should I recommend they immediately replace the drive or is SMART testing just a waste of time?



  2. #2
    3 Star Lounger
    Join Date
    Mar 2010
    Thanked 40 Times in 31 Posts
    As usual, disclaimer: "Do it at your own risk"
    I design hard drive chips.
    Hard drive data have many levels of redundant protections. A few failed bits are no problem from retrieving the true bit value. In fact, the magnetic shape of the signal looks terrible at times. We look at streams of magnetic signals to arrive at the true value. The sample size is large. It is not uncommon that you find quite a bit of false magnetic signals. The error correction methods and schemes are that the true bit value is very very solid.

    Software is to find faults. The more faults it finds the better 'value' the software is.
    An example of 'bad bits' can be compared to looking at a recordable DVD. The pits in disc are not perfect. But the more 'perfect' DVDR is a better one.

    I would trust the hard drive SAMRT result. When it says 'danger' it means all its correction tools are not good enough and some storage bits are failing or unreliable, or non repeatable. Time for immediate action.

    In some cases, even after the SMART warning, the hard drive could still work for a month or months. Trust me, when SMART says it fails the hard drive fails. Then why it seems still working? Accuracy is measured in statistics. If you read 2^27 times and ONE bit is bad, it is acceptable, but not at 2^26 times. For a picture file, a one bit flip is nothing. For a bank, a one bit flip could be pretty bad if the computer is making billions and billions of hard drive access or account transactions.

    My advice:
    Still advise customer to backup, backup, and backup.
    If SMART reports failure, immediate action to transfer everything to a new hard drive.
    Warning: making a drive image is not good but a quickie if needed. (You image the good, bad, warts and all). Best is do file backup.
    May use the old drive for temporary use as secondary drive. Customer may love that when the drive may not die or show ill effect until months later. Customer would appreciate much if it fails in a day or a week.

  3. The Following User Says Thank You to scaisson For This Useful Post:

    pjustice57 (2011-05-26)

  4. #3
    Super Moderator RetiredGeek's Avatar
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    Mar 2004
    Manning, South Carolina
    Thanked 1,608 Times in 1,452 Posts
    I tell my customers: "Drives are CHEAP! Data Loss is EXPENSIVE! You make the call."
    May the Forces of good computing be with you!


    PowerShell & VBA Rule!

    My Systems: Desktop Specs
    Laptop Specs

  5. #4
    WS Lounge VIP
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    Dec 2009
    Thanked 1,125 Times in 1,048 Posts
    Backup is always the correct answer, even if the drive is OK. It only takes one power failure to turn a good disk into rubbish.

    cheers, Paul

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