Mac OS X is a powerful and advanced operating system, which supports a number of storage media like hard drive, external hard drive, USB drive, CD, DVD, and memory cards to store your valuable data. The external hard drives are generally used to take backup of your valuable data and safeguard your data. They can also be used to move data from one system to another. However, in some situations, the external hard drive may become inaccessible and you come across critical data loss situations. At this point of time, you need to perform Mac data recovery to work around the problem, if backup is not available.

Sometimes, Mac OS X operating system cannot read the external hard drive. When you attempt to extract data from an external hard drive, you may come across the below error message:

“The disk is unreadable: Do you want to initialize it now?”

After this behavior of Mac OS X operating system, when you attempt to fix the problem using Disk Utility tool, further error message may occur stating:

“Verify and Repair volume “disk1s3” Checking Journaled HFS Plus volume. Invalid node structure Invalid B-tree node size Invalid node structure Invalid B-tree node size Volume check failed. Error: File system verify or repair failed.”

As stated in the above error messages, the problem is caused by missing or damaged data structures, hard drive profiles, and library files of your Mac OS X computer. It may occur because of node structure corruption or file system corruption.

As mentioned in the first error, your Mac OS X hard drive can not be used until it is initialized. The disk initialization is a three step process, which removes all your valuable data from hard drive.

The above problem can be caused by various reasons, such as iNode corruption, file system corruption, invalid system files, and more. It is required to replace the damaged data structures, to fix the problem and perform Data recovery Mac.

If you fail to replace the damaged system files without formatting hard drive, you need to use Mac recovery software to retrieve lost data from hard drive. The applications enable you to systematically scan entire hard drive and extract all lost data from it. Such Mac File recovery tools are extremely easy to use with simple graphical user interface.

Stellar Mac Data Recovery software successfully recovers lost, deleted, missing, or inaccessible data from Mac-supported storage media. The software works well with Mac OS X 10.6 Snow Leopard, 10.5 Leopard, 10.4 Tiger, and 10.3.9 Panther. It extracts data from all HFS, HFS+, HFSX, HFS Wrapper, and FAT file system volumes.