Thursday, 3 February 2011

MacBook Pro 17" fsck error EXITED WITH SIGNAL 8

Rob brought in his 17" MacBook which wouldn't get past the white screen with a gray apple and spinning dotty thing. I tried resetting the PR RAM. Next I tried single user mode with /sbin/fsck -yf. Results as shown:
Rebuilding B-Tree
could not repair volume
/dev/rdisk1s2 (hfs) EXITED WITH SIGNAL 8

Looked this up and found quite a few people with MacBook Pro's having the same error, looked to be related just with the file system and probably not a hard drive fault (hopefully). As Rob needed stuff off the HD I found only one command which might fix it, found it here:

  1. Boot off the OS X CD (reboot, hold C while booting).
  2. The installer will load up, go to Utilities in the menu and run Terminal.
  3. Type df and look for the drive that has your Mac system mounted---you'll have to unmount this. On my MacBook Pro, it was /dev/disk0s2.
  4. Type umount /dev/disk0s2, replacing disk0s2 with whatever disk your OS lives on.
  5. Type fsck_hfs -r /dev/disk0s2. If you umounted the wrong thing, it will complain that you can't repair a mounted drive. Go back and umount the right thing and repeat this step.
I found netbooting to a deploy studio image had the same results as using the install disk. Coinsidence or not it, it was disk0s2 that was the OS X partition.

Anyway, it came up with another error, saying volume could not be repaired. I put it in target disk mode and mounted it on another MacBook Pro. It came up saying that there are serious issues with the volume which cannot be repaired, it is only being mounted to retrieve files which should be backed up immediately.

I used Migration Assistant to get the user account across, and copied other erroneous files. I re-partitioned and re-imaged the macbook pro and all is well.



  1. Tried this, but I think I unmounted in safe mode. Now getting 'permission denied' in command line.

  2. Update: After these two steps:
    Type umount /dev/disk0s2, replacing disk0s2 with whatever disk your OS lives on.
    Type fsck_hfs -r /dev/disk0s2. If you umounted the wrong thing, it will complain that you can't repair a mounted drive. Go back and umount the right thing and repeat this step.

    I received this msg:
    "hfs: No such file or directory
    Can't stat hfs
    Can't stat hfs: No such file or directory
    -r: no such file or directory
    Can't stat -r
    can't stat -r: No such file or directory
    ** /dev/rdisk0s2


    My head is spinning. NO forums or anywhere able to help. You are the only search that has an answer to this error message. I suspect I am going to have to reinstall my OS. I hope you can help.

    1. Hi Hap,

      I think I was just lucky that my Hard Drive was just about fixable. It could just be that your hard drive is too far gone to be fixable?

      One more thing you can try is attaching it via a Firewire cable to another Apple Mac computer (assuming you've got another) and using the feature called "target disk mode" to mount the Hard Drive from the broken computer onto another computer. You could then try and use disk utility, or perhaps run this command from the other computer or use other software to try and fix the hard disk.

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  4. All very helpful, and I appreciate you posting this, but this is really helpful if you don't have an install disk. I bought my mac second hand, and it didn't come with an install disk. Think you could point me to somewhere where it shows you how to make one?

    1. If you've got another Apple Mac handy and a firewire cable you could "Target Disk Mode" and modify the hard drive from the working mac.

      The only other workaround is to take it to an Apple Store. They can do Netboot and run the above fix pretty easily. Might even do it for free!