Hard Drive errors are very common in any computer operating system, including Mac OS X. The disk errors generally occur due to corruption of critical data structures, system files, and metadata structures of your Mac OS X hard drive. In such cases, the system may not boot and you will not be able to access your precious data from Mac OS X hard drive. This behavior causes severe data loss and requires Mac recovery to be resolved, if there is no backup in place.

Mac OS X operating system offers an inbuilt disk repair tool to handle such situations, known as Disk Utility. When you run the disk utility on an affected Macintosh disk, you may encounter the following error:

“Checking disk “Mac OS X”.
Checking “Mac OS Standard” volume structures.
Checking wrapper System file.
Checking “Mac OS Extended” volume structures.
Checking for locked volume name.
Checking extent B-Tree.
Checking extent file.
Checking catalog B-Tree.
Problem: Invalid B-Tree Header, 0, 0
Checking catalog file.
Problem: MountCheck found serious errors.
Checking catalog hierarchy.
Checking volume bit map.
Problem: Overlapped extent allocation, 4, 4430
Problem: Overlapped extent allocation, 4, 4430
Checking volume info.
Problem: Volume Header needs minor repair, 1, 0
Repairing the disk.
The volume “Mac OS X” was repaired successfully.
Volume “Mac OS X” had overlapping extents. Two or more files were accessing the same disk block. Aliases to the damaged files have been created in the folder “Mac OS X damaged Files”.”

The disk can not be accessed in such circumstances. To extract data from affected Mac OS X hard drive, you need to identify the root cause of this behavior and perform data recovery Mac by fixing it.

Cause

As stated in the above error message, the problem occurs due to various reasons, including overlapped extent allocation, volume header corruption, volume bitmap corruption, and mount check errors. Such problems may prevent the disk from being mounted.

Resolution

Try repairing the disk using Disk Utility tool. If it does not work, format the hard drive, reinstall operating system, and then restore data from an updated backup. Mac data recovery tools are particularly designed to carry out in-depth scan of entire Mac OS X hard drive and salvage all lost data from it. You need not to be a technical expert to use these tools as they are totally easy to use.