Data carving is the lowest level of recovery, but will work on very corrupted media. It is normally considered a last resort but on some devices can actually produce extremely good results.

Data carving initially works on file signatures. This is by looking at the start of a file, and recognising a series of bytes as being unique to a file type. For instance, a JPEG file will always start with 0xFF 0xD8 0xFF. Some carving programs also try and find the end bytes of a file, but these are typically far less defined.

Carving, initially assumes that a file is sequential, and for many short files this is the case. For long files, or on a heavily used disk, or full disk, the chance of sequential files decreases, leaving fragmented files. To recover fragmented files is a skilled process, but CnW will attempt this for several common types of file, such as JPEG and AVI.

Positive aspects of data carving
● Works with any file system, even a missing file system
● Works when there is no files system structure available, eg on disk with the start missing.
● Works when parts of the disk have been totally corrupted or overwritten.

Limitations of data carving
● File name and directory structure is lost
● Exact file length may not be known
● Fragmented files are not recovered by default
● Files are only recovered if a unique signature is know.
● Disk compression may cause problems
● Will not work with many Reiser FS files

CnW Solutions to typical carving limitations
● CnW will often create a meaningful file name based on meta data within the file
● CnW will parse the file and often determine the original exact file length
● Several files types can be processed to reconstruct fragmented files
● NTFS compression can be detected and handled on a cluster by cluster basis
● There is no solution for Reiser FS - except CnW can recover many deleted Reiser files

Fragmented files and data carving
CnW Recovery is one of very few programs that can carve out files and then process the fragments when they are not in sequence - ie fragmented. This is Smart Data Carving. The current list it can handle includes. From about V4.50, the functions below are best performed by the specific wizards

● AVCHD/MTS
● 3GP/MOV, GoPro (Use Gopro recovery program).
● AVI

Conclusion
Carving has limitations but can at times be the only solution to finding files on a very corrupted disk, or within unallocated space. The CnW Recovery enhancements assist with recovery more than a simple routine that searches for headers and signatures only.

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