Grahf85

Q: OSX El Capitan Wont Boot

Hi.  I have El Capitan and Windows 10 installed on my macbok pro via bootcamp.  This morning I tried starting my computer to OS X and it loaded the status bar under the apple logo and shut off.  That's all it does every time I try to start it.  Windows 10 boots fine.  That's what I'm on now.  When I booted to verbose mode it says "disk0s2 I/O error. The volume OSX Yosemite could not be verified completely."  And then some other stuff.  Does anyone know what's going on here?  Im going to try running disk utility next.  image1.jpeg

MacBook Pro, Mac OS X (10.7.3)

Posted on Aug 2, 2016 12:02 PM

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Q: OSX El Capitan Wont Boot

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  • by lllaass,Apple recommended

    lllaass lllaass Aug 2, 2016 12:06 PM in response to Grahf85
    Level 10 (188,002 points)
    Desktops
    Aug 2, 2016 12:06 PM in response to Grahf85

    That error means either:

    - The disk got corrupted and can't be repaired because of a software problem

    or

    - The disk has physically failed.

     

    - Boot to Recovery and repair the startup disk

    OS X: About OS X Recovery - Apple Support

    https://support.apple.com/en-us/HT201314

    - If it is repairable reinstall the OSX.

    How to reinstall OS X on your Mac - Apple Support

    https://support.apple.com/en-us/HT204904

    - If you do not have a backup use disk utility to restore the internal disk to an external disk so you can try to recover data.

    Then format the startup disk and do a fresh install of OSX

  • by macjack,Apple recommended

    macjack macjack Aug 2, 2016 12:07 PM in response to Grahf85
    Level 9 (55,682 points)
    Mac OS X
    Aug 2, 2016 12:07 PM in response to Grahf85

    That's a kernel panic, see this Apple Support Topic:

    OS X: When your computer spontaneously restarts or displays "Your computer restarted because of a problem." - Apple Supp…

    Specifically: Troubleshooting a recurring kernel panic.

  • by Grahf85,

    Grahf85 Grahf85 Aug 2, 2016 12:18 PM in response to Grahf85
    Level 1 (8 points)
    Desktops
    Aug 2, 2016 12:18 PM in response to Grahf85

    The last thing I was doing was playing around in Xcode.....could that have ruined my partition????

    First aid didn't work in disk utility Going to try what you just suggested....

  • by Grahf85,

    Grahf85 Grahf85 Aug 2, 2016 12:26 PM in response to Grahf85
    Level 1 (8 points)
    Desktops
    Aug 2, 2016 12:26 PM in response to Grahf85

    So here's what I'm thinking...

     

    I can access all of my data on the os x partition through my windows 10 partition.  I'm going to pull everything I want from os x while running Windows 10 and put it on a thumb drive.  Then I will format the OS X partition, re install os x, and then put my data back on OS X with my thumb drive. 

     

    Am I missing anything?

  • by lllaass,

    lllaass lllaass Aug 2, 2016 12:37 PM in response to Grahf85
    Level 10 (188,002 points)
    Desktops
    Aug 2, 2016 12:37 PM in response to Grahf85

    Nothing that I know is missed.

    However, backup your Windows data too since reinstalling OSX might mess up Windows but should not.

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Aug 2, 2016 12:51 PM in response to Grahf85
    Level 9 (60,714 points)
    Desktops
    Aug 2, 2016 12:51 PM in response to Grahf85

    Data are written to Hard drives in a semi-redundant form, and read back through Error-Correction Hardware. If a read error occurs, the data are re-read, up to 100 times. Then the drive may do a "recalibrate" (seek track 00), which on some (not all) drives, produces and audible click as the switch at track 00 is engaged. Then the process is repeated, typically for 100 cycles. At the end of this process, the data have been re-read 100*100 times, and could not be corrected into good data.

     

    Only at this point does the system throw an "I/O Error".

     

    You have at least one block that is completely Bad, and its data cannot be retrieved. The only way to correct that block is by re-writing known-good (that is NEW) data into that block.

     

    The data may come clean with a re-write. If not the drive controller can often substitute a spare block from nearby from its stash of "spares", reserved for just this purpose. But just how many blocks are bad is unknown. and whether a spare is available is unknown. The drive may have had it, or maybe not. It will take many hours to find out for sure.

     

    The "classic" way to recover from this, once you have attempted to salvage what you can from this drive is to write every block with Zeroes, which takes all afternoon.

     

    • The way to make rapid progress is to boot from another MacOS drive, and if one is not available, to make one. Then you have full MacOS and additional Utilities available to work from while you do what you need to do.

     

    • The way to get bogged down for days, and stress yourself out in the process, is to use only primitive, one-at-a-time Recovery tools to do this work. It is like working through a tiny peep-hole at the problem.

  • by Grahf85,

    Grahf85 Grahf85 Aug 2, 2016 1:09 PM in response to Grahf85
    Level 1 (8 points)
    Desktops
    Aug 2, 2016 1:09 PM in response to Grahf85

    I'm really not happy about this..... 

  • by Grahf85,

    Grahf85 Grahf85 Aug 2, 2016 9:03 PM in response to Grahf85
    Level 1 (8 points)
    Desktops
    Aug 2, 2016 9:03 PM in response to Grahf85

    OK OS X is back in action....

    Thanks for your support..............

    Stupid Hard Drive.

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Aug 3, 2016 7:33 AM in response to Grahf85
    Level 9 (60,714 points)
    Desktops
    Aug 3, 2016 7:33 AM in response to Grahf85

    Stupid Hard Drive.

     

    Amen to that!

     

    Regardless of the eventual outcome for this troublesome drive, you should think of this as your as your wakeup call for having a Current Trusted backup available at all times. A large (but slow) external drive at least 3 times the size of what you want to save, and starting up Time Machine (harder to describe than to actually do it) will yield a complete Backup in an afternoon. After that, Time Machine will try to do incremental Backups on roughly an hourly basis.

     

    Time Machine's "claim to fame" is that Time machine is the backup that actually gets done, without interfering your ability to get your work done. It works at low priority in the background, and does incremental Backups (nominally hourly) without further intervention.