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There is some error reported when I run Disk Utility and verify the root volume on my OS X MacBook. So I boot and CMD-S into the shell mode and run /sbin/fsck -fy.

Errors are like:

** Checking catalog file.
   Missing thread record (id = ...)
   In correct number of thread records

** Checking catalog hierarchy.
   Invalid volume file count
   (It should be ... instead of ...)

** Repairing Volume
   Missing directory record (id = ...)

I'd like to know what is the cause of the above errors? Hopefully I will be more careful in the future to prevent them from happening again.

p.s. I am using a SSD and so I assume mechanical hard disk error is less likely. Thanks!

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migrated from serverfault.com May 25 '10 at 3:39

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1 Answer 1

up vote 0 down vote accepted

They are all errors related to the filesystem on the disk having inconsistencies and/or corruption - the details are somewhat unimportant unless you want to go read the HFS spec and write some code around fixing it.

In terms of getting the disk back to working, once fsck is finished, try booting from the CD with an OSX startup disk and running the disk utility to try a repair in that tool. Several people have reported that this succeeded for them (some after more than one attempt).

If that fails and you still cannot mount/boot from the volume you have a couple of options. One is to mount the drive in Linux and attempt to copy off anything of importance, so you can basically reformat the drive and start from scratch. This also has the benefit of being free to try, it's usually worth a shot either way.

The other (non-free) approach is to look at one of the commercial disk repair utilities. I have used Disk Warrior for this myself, Norton have something similar.

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