Could I have corrupted my HD during an OS install?

Discussion in 'Mac Basics and Help' started by markburgle, Feb 20, 2016.

  1. markburgle macrumors newbie

    Feb 20, 2016
    Hi all, I just acquired a 2nd-hand Macbook Pro from 2012, and during setup it was v. slow, and kept freezing during spotlight indexing - disk utility told me the HD could not be repaired without formatting the drive.

    So I did this, and ran a repair which now said the HD was OK. I was able to boot to recovery mode and start installing an OS (Lion) over the internet, but it kept freezing during this process, or the "time remaining" count would get to zero then reset to read 1 hour 40 mins +-.

    Anyway after doing a hard reset to escape from yet another failed install attempt, the drive has disappeared. I can boot into recovery mode, but only Mac OSX Base System is showing, plus the Superdrive. Apple Hardware Test detects no problem. Is the HD broken? Did I do it, or was it on its way out already?

    All help much appreciated, thank you!
  2. chown33 macrumors 604

    Aug 9, 2009
    descending into the Maelström
    Your description is symptomatic of a failing disk drive. Even if the SMART status says it's OK, the disk can still be failing.

    Basically, the disk is unable to read data accurately, using internal checks, such as CRCs. Its remedy when this happens is to reread, up to some defined limit like 100. If the checks succeed at some point, say the 34th read attempt, then the block is handed over to the CPU. Unfortunately, it took at least 34 times as long as normal to read that block. Then repeat this for every block read from disk, and substitute a random number of reads for each, but less than the hard failure limit. Because all the blocks eventually were read correctly, it seems as if the disk is working. The fact it took many times longer than normal doesn't play a role.

    And if the disk eventually fails to read at all, then it won't even be detected, which is the latest symptom.

    Short answer: Yes, it sounds like a failed disk. It was probably failing already.

    If you have an external disk-drive case to put it in and test it on another machine, that might be useful. If not, new HDs are relatively inexpensive.
  3. markburgle thread starter macrumors newbie

    Feb 20, 2016
  4. Fishrrman macrumors P6


    Feb 20, 2009
    Before you condemn the drive itself as "failed", be aware that the thin internal ribbon cable (from the drive to the motherboard) on these models can become flaky and cause problems similar to what you're experiencing now.

    Best way to check is to physically remove the drive and put it into a USB3 enclosure.
    If the drive seems to "stabilize" after doing that, it could point to the ribbon cable, instead of the drive itself...
  5. markburgle thread starter macrumors newbie

    Feb 20, 2016
    Thanks Fishrrman, so if it is the ribbon that's faulty, is that a lot harder to fix than swapping out the drive? I've now done as you suggested and put the new Macbook's drive into an external enclosure, where it is readable from my old laptop. And I put the drive that was in the enclosure into the new Macbook where... it's invisible!
  6. Fishrrman macrumors P6


    Feb 20, 2009

    Go here:"_Unibody_Mid_2012
    (2012 MBPro general section)

    Repair guide for replacing hard drive ribbon cable is here:

    I -think- this is the part you need:
    (this is from site).

    Be aware that you might be able to get this same part cheaper (ebay, etc.)

    Research the part number before ordering.
  7. markburgle thread starter macrumors newbie

    Feb 20, 2016
  8. Ebenezum macrumors 6502a

    Mar 31, 2015
    Ribbon cable is likely faulty.

    I have done several ribbon cable changes myself and as long as you have steady hands it is possible. Connections are very small so you likely need a magnifying class to see them and pincer to connect them. Be careful with the connections, they are fragile!

    If after looking at the instructions Fishrrman posted you aren't certain that you can replace the ribbon cable it might be a good idea to pay for a professional to install it...
  9. markburgle thread starter macrumors newbie

    Feb 20, 2016

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