We know that in Mac OS X hard drive, a file usually exists as fragments by which Mac systems refer these fragments as extents. To hold information about these fragments, a catalog file, called as extents B-tree, is used. But sometimes, you may observe errors with these extents. In such cases, the corresponding file becomes inaccessible to the system. Disk Utility and fsck can detect such files.
However to recover the lost file, you require recent file backup. If file backup is unavailable, faulty or not updated, Mac Recovery applications offer the solution. You may get following error message while checking your drive with Disk Utility or fsck command line utility: “Missing extent” The error message suggests that these repair utilities can’t correct the issue.
Missing extent error message implies loss of file extents. There is a record to keep track of total number of extents for a file. But when the actual number of extents is found lower than expected, the above error message generates and the file or its part gets lost. When this error message displays, you may also see a number, which is actually its inode number.
Inode helps locating the file on hard disk. So, you can determine the affected file. The file can be a data file or system file. For recovering data file, there are two options available:
• Recent file backup
• Third party Data Recovery Software Mac tools
You can attain system file recover using BOM. BOM stands for Bill Of Materials. It is used by Mac OS X installer to know about files required to be removed, installed or upgraded. However if file backup is available and you can restore the missing information, you can follow either of these solutions to work for error message problem:
Backup all the possible data, erase the affected volume and reinstall Mac OS X
For Mac OS X 10.4.2 and later volumes, you can use Disk Utility or fsck
Third party disk repair applications can also be used
In case of file backup errors or absence, use Mac Recovery tools to recover lost file. These specific applications scan the drive for recovering data. Data Recovery for Mac is the robust tool to recover lost data. It is a read-only application with rich support of Data Recovery Mac features. The application supports Mac OS X 10.5.x, 10.4.x and 10.3.9. It recovers data in all possible data loss case. The application is compatible with HFSX, HFS+, HFS Wrapper, HFS and FAT file systems.
Missing files in FAT32-folders often has to do with filenames. OSX does not accept a folder where there is a file starting with ¿ for instance. One sollution is to ZIP the problematic folder when the drive is cabled to a PC. (The ZIP-function in Windows warns you about incompatible characters. Rename these files before making the ZIP filder.) If Windows let you create the ZIP-file, then the Folder is OK and now readable from OSX.
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