Carbon Copy Disk Read errors on HD:Disk Utility/First Aid says OK???

Discussion in 'macOS High Sierra (10.13)' started by Julien, Jun 9, 2018.

  1. Julien, Jun 9, 2018
    Last edited: Jun 9, 2018

    Julien macrumors G4

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #1
    Have a Mac mini and use an external SSD as my boot drive. I use the Internal HDD for a CCC backup. Lately CCC has been falling to complete a Clone and says there are Read Errors on the disk. If I reformat it will make a Clone and then will work for a few days (1 backup every night) and then quite. The number of errors is now at 316 and keeps increasing.

    Disk Utility/First Aid says all is fine and I have even used Secure Erased to write over the disk and it works fine.

    Is the disk defective and how do I tell? Does Disk Utility/First Aid not really work well or is it right?

    Also not sure what the best forum to post in so Mods move if you feel it is wrong.

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  2. treekram macrumors 68000

    Joined:
    Nov 9, 2015
    Location:
    Honolulu HI
    #2
    Take CCC at it's word that it had read errors. HDD read errors may not necessarily be consistent. So for the same sector on the disk, it might fail but then it might read OK. Programs that try to recover data from failing disks will do multiple passes on a sector when it gets a read error and it's not unusual that in doing the multiple passes, it will be able to read the data.

    First Aid does a cursory check - it does not check every sector.

    In Disk Utility, click on the APPLE HDD ... instead of the "Carbon Copy". Look at the S.M.A.R.T. status (towards the bottom middle of the screen). Does it say verified? S.M.A.R.T. is a standard whereby data on the HDD is collected. I'm pretty sure that all of the disk read errors would be counted as part of S.M.A.R.T. There's some criteria that Apple uses to figure out what is verified vs. what is not - whether it's reached that threshold is unknown as Apple doesn't publish the criteria. However, I would hope that 316 errors in one pass of Carbon Copy would qualify as non-verified. But you never know.

    There are apps that can test every sector. If it turns out that only a small portion of the disk has gone bad, it's also possible that using these programs you can flag it and the OS won't use those sectors and then you can go on using the HDD. However, with the cost of these programs, the cost of HDD's being what they are and the likelihood of your HDD being on the path of failing, I wouldn't bother - just buy a new HDD.
     
  3. crjackson2134 macrumors 68040

    crjackson2134

    Joined:
    Mar 6, 2013
    Location:
    Charlotte, NC
    #3
    Okay, so the read errors are coming from the SSD as I read it.

    It seems some cells are failing on a regular bases. Reformatting the drive maps out the defective areas from the usable filesystem space. Then after a few days, even more cells are failing and the dance starts all over again.

    First Aid app can't test the SSD at the low level. It can only realign the file system to the good cells...

    I would replace the drive ASAP if it were me... It's failing fast... Catastrophe will probably happen fairly soon...
     
  4. Julien, Jun 9, 2018
    Last edited: Jun 9, 2018

    Julien thread starter macrumors G4

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #4
    Yea, was about to order an SSD to use as a CCC backup disk. Thought I would post and see if anyone had a better idea. Guess that is the best path and just 'forget' the mini's internal HDD and let it sit empty.

    Also S.M.A.R.T. status for APPLE HDD.... says "Not Supported". What does that mean?

    No it is the internal HDD that is showing the read errors. My SSD seems fine (no errors reported), at least according to CCC.

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  5. crjackson2134 macrumors 68040

    crjackson2134

    Joined:
    Mar 6, 2013
    Location:
    Charlotte, NC
    #5
    Okay, different type of drive, but sounds like it's still failing. It just happens a little differently. I good HD disk utility could tell you for sure, but it's likely not worth the investment in software. You can buy a replacement drive that cost no more or even less than a utility.

    I use Spinrite 6 when it's important, but usually it's not.

    Just grab another drive and don't give it a second thought.
     
  6. Julien thread starter macrumors G4

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #6
    Guess I see the answer now. I left it highlighted for a couple of hours and it changed from "Not Supported" and now it says "Failing".

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  7. crjackson2134 macrumors 68040

    crjackson2134

    Joined:
    Mar 6, 2013
    Location:
    Charlotte, NC
  8. Julien thread starter macrumors G4

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #8
    Already ordered (SSD). Hate spending money for "insurance" but do LOVE to play.:D Will also test speed using Blackmagic and use the faster SSD for my boot drive (although the USB 3 is probably the "chock point").
     

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