How to fix the Invalid Sibling Link error

by introspectif

I got this error after a software update that turns on journaling on the Mac OS X filesystem.

The update instructs the user to reboot using the Install Disk and running a Repair operation using the Disk Utility. That was when I discovered the error. Apparently, even the Repair operation could not fix the error.

The solution

Here is the solution, adapted from macosxhints.com:

  1. Reboot into Single User mode (restart, and press and hold Command-S). You will see a black screen with a command prompt.
  2. Type fsck_hfs -r /dev/disk0s2 and press Enter. This will repair the error, and will take a while (~10 minutes). Wait for the operation to complete i.e. until the command prompt appears again.
  3. Type fsck -fy and press Enter. This will check the filesystem again, and confirm that it is now OK. Again, wait for the operation to complete i.e. until the command prompt appears again.
  4. Type reboot and press Enter. This will restart the system to normal.

Good luck!

Why this works

Actually, this is more of why I think this works. (UPDATE 11/01/09: Karl has given a more accurate explanation in comment #102. Thanks, Karl!)

Booting into Single User mode allows you run administrative tools (in our case, fsck, a disk repair tool) without mounting any hard disk partitions or starting any system services. This allows fsck to repair parts of your hard disk (in particular, the /usr directory) which are not usually possible to repair using Disk Utility from within Mac OS X that is loaded from the hard disk itself.

So, alternatively, I think you could in fact use the Disk Utility that is loaded from the Mac Installation DVD to achieve the same success. However, this method eliminates the need for the disk, and thus is useful for those who no longer have the Installation DVD or are just too lazy to find it. Plus, if this is your first time booting into Single User mode or typing such cryptic commands as the above, you’ll find it way cooler ;-)

Why this might not work

As explained above, this method will work only if you have an error in the part of your hard disk that is not normally accessible when you are running Mac OS X. If the problem you face is actually from an external hard disk, I believe that Disk Utility should suffice to correct the error, if the error is repairable (i.e. the error is not because of a hardware defect).

However, if you read some of the comments below, this method has worked for some to correct some errors on external hard disks which Disk Utility cannot; so it’s still worth a try. But there are also some who report that this method does not work, and I suspect that it is because their hard disk is physically defective, in which case, the only solution is to get a new hard disk.

Signs of success

From external web sites

From the comments

A cool thing that they’re all odd-numbered.

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P.S.:

  • If this worked for you, please do let me know here :)
    It may serve as a confirmation so that other people would be willing try this method too.
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