iMac will no longer boot after failed First Aid

Discussion in 'macOS Sierra (10.12)' started by dyl003, Apr 13, 2017.

  1. dyl003 macrumors newbie


    Apr 13, 2017
    I have a late 2010 27" iMac running the latest version of Sierra. There is approximately 70% of the hard drive available and it has 8gb ram.

    Yesterday my computer was running particularly badly with the spinning ball throughout the day which would last for several seconds. This was happening in all apps. I rebooted twice but it did not improve.

    I decided to try Disk Utility. On scanning my main drive I was told it found errors and required me to try First Aid in recovery mode. I did this and it could not fix the error telling me 'First Aid process has failed, if possible back up data on this volume'.

    After a couple of failed attempts I restarted the iMac but it will no longer boot. It gets halfway along the progress bar on startup after chiming then just switches off.

    I tried unplugging all peripherals but that didn't help. I have followed instructions to reset the NVRAM but that hasn't helped either.

    Luckily I do keep backups.

    Any suggestions what to do next as currently it is pretty much a brick!
  2. keysofanxiety macrumors G3


    Nov 23, 2011
    Sounds like a corrupted/failing HDD. What you can do is plug in an external hard-drive or USB stick. Then:

    1) Hold CMD+R on startup. This will boot into macOS Utilities.
    2) Open Disk Utility and format the external hard-drive/stick as macOS Extended (Journaled) on the GUID partition map.
    3) Close Disk Utility and select Reinstall macOS. Point it to your freshly formatted disk.
    4) This will then install macOS (though it'll take some time as you have USB 2!) and boot into it.

    Now that we've got a working OS, we can run some diagnostics. Please be aware the system will be really slow when running from this external disk.

    In your new OS, download and run SMART Utility. Anything other than 'Passed' would indicate the internal HDD is faulty:

    If it's confirmed to be faulty, it would be best to swap out the internal drive for an SSD. The reasoning for this is that SSDs are considerably more reliable, significantly improve performance compared to a standard HDD, and if you're getting your hands dirty with a hard-drive replacement then it might as well be for an upgrade. Instructions are here:

    If the internal disk passes, you can hopefully access the internal Macintosh HD data through your external OS, then backup any important data from there. Once you've done that, hold CMD+R on startup again and format the internal drive through Disk Utility, then reinstall macOS.

    Regardless, it's almost certainly a faulty hard-drive, based on the age of the machine alone.
  3. dyl003 thread starter macrumors newbie


    Apr 13, 2017
    Thanks keysofanxiety. The computer has been struggling a lot at startup for the last year or two now. It takes a good 15-20 mins for it to settle down after startup so I guess it's no surprise the HD appears to have failed especially as I use it all day every day.

    I will purchase a new SSD.
  4. Wheresjerry macrumors newbie


    Jan 2, 2016
    Happened to me. Turns out the hard drive portion of my 1Tb Fusion drive crap out. I tried everything including a failed reinstall of OSX.
    I replaced the drive to a 500gb SSD Very pleased with switching to the SSD drive
  5. dyl003 thread starter macrumors newbie


    Apr 13, 2017
    I came to the same conclusion. Have arranged for a new 500gb SSD fitting in a few days time.

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