HT204904: How to reinstall OS X

Learn about How to reinstall OS X
Francis Yap

Q: Yosemite crash

Hi, my MAC after turn ON, half way loading then it shut down, try reset everything include PRAM still same problem.

 

Now I want to try reinstall the OS, will it wipe the drive? I don't have backup so it's very important not to remove the file.

MacBook Air, Mac OS X (10.7.2), 256GB SSD, 1.8GHZ i7

Posted on Mar 27, 2016 9:15 PM

Close

Q: Yosemite crash

  • All replies
  • Helpful answers

  • by BobHarris,Apple recommended

    BobHarris BobHarris Mar 28, 2016 6:12 AM in response to Francis Yap
    Level 6 (19,257 points)
    Mac OS X
    Mar 28, 2016 6:12 AM in response to Francis Yap

    Hi, my MAC after turn ON, half way loading then it shut down, try reset everything include PRAM still same problem.

    Start by trying to boot into Safe Mode

    <http://support.apple.com/kb/ht1564>

     

    If you can get booted in Safe mode, see if you have kernel panic reports

    Kernel Panic reports: "/Library/Logs/DiagnosticReports"

    <http://support.apple.com/kb/ht2546>

    <http://support.apple.com/en-us/HT200553>

    The panic report should have "panic" in the file name.

     

    If you do have kernel Panic reports, please post 2 or 3 as replies to this thread.

     

    If you cannot boot into Safe mode, try recovery mode, and run disk utility to check your boot disk

    <OS X: About OS X Recovery - Apple Support>

     

    Now I want to try reinstall the OS, will it wipe the drive? I don't have backup so it's very important not to remove the file.

    Generally, installing the OS over top of an existing install will not erase things, HOWEVER, unless you are re-installing the same version or a newer version, often times the installer will not install an older version on top of a newer version.

     

    NOTE:  I would try to get the current system booted if possible, before going down the re-install path.

     

    In theory you could use Recovery mode and Disk Utility to make a backup

     

    You could also use Recover mode to make a clean OS X install on an external disk, and then use that external disk to salvage data from your boot disk.

  • by Francis Yap,

    Francis Yap Francis Yap Mar 28, 2016 7:22 AM in response to BobHarris
    Level 1 (4 points)
    Mac OS X
    Mar 28, 2016 7:22 AM in response to BobHarris

    Hi Bob,

     

    Already tries safe mode, it took very long time and eventually shutdown

     

    Tried the disk utility first aid repair but still same issue.

     

    what is the best option I have

  • by BobHarris,Apple recommended

    BobHarris BobHarris Mar 28, 2016 8:21 AM in response to Francis Yap
    Level 6 (19,257 points)
    Mac OS X
    Mar 28, 2016 8:21 AM in response to Francis Yap

    If there is an Apple Store near by, make a Genius Bar appointment, but MAKE SURE they do not do anything that will erase your disk.  You can always say "Thank You", and go home to consider other options if it comes down to a reformat.

     

    I would try the Recovery Mode -> Disk Utility -> Select an external disk, then Disk Utiliyt -> Edit -> Restore where you specify the internal disk as the "Restore From" device, and an external disk as the destination, and see if you can get a backup.

     

    If that doesn't work, I would see about installing a new OS X on an external disk from Recovery Mode (or another Mac), then boot from the external disk and see what you can do to backup your internal disk.

     

    Once you have a backup (2 would be better), you can reformat the internal disk, install a clean OS X, then restore your data from your backup(s).

     

    Feel free to get a 2nd opinion

  • by Eric Root,Apple recommended

    Eric Root Eric Root Mar 29, 2016 12:25 PM in response to Francis Yap
    Level 9 (69,582 points)
    iTunes
    Mar 29, 2016 12:25 PM in response to Francis Yap
  • by Francis Yap,

    Francis Yap Francis Yap Mar 30, 2016 5:13 AM in response to Eric Root
    Level 1 (4 points)
    Mac OS X
    Mar 30, 2016 5:13 AM in response to Eric Root

    When I go to CMD + V mode I can see the last 2 message flash before it shutdown automatically, any clue


    Boot task failed: fsck-safe

    <Emergency>: Shutting down in 3 seconds.

  • by BobHarris,

    BobHarris BobHarris Mar 30, 2016 5:54 AM in response to Francis Yap
    Level 6 (19,257 points)
    Mac OS X
    Mar 30, 2016 5:54 AM in response to Francis Yap

    Google found this post, but I'm not sure they actually really resolved the issue.

    <https://apple.stackexchange.com/questions/155209/macbook-pro-2011-rebooting-on-s tartup>