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Some file systems, such as Btrfs, HAMMER, ReFS, and ZFS, use internal data and metadata checksumming to detect silent data corruption. In addition, if a corruption is detected and the file system uses integrated RAID mechanisms that provide data redundancy, such file systems can also reconstruct corrupted data in a transparent way. [18]
File carving is the process of trying to recover files without this metadata. This is done by analyzing the raw data and identifying what it is (text, executable, png, mp3, etc.). This can be done in different ways, but the simplest is to look for the file signature or "magic numbers" that mark the beginning and/or end of a particular file type ...
The most common data recovery scenarios involve an operating system failure, malfunction of a storage device, logical failure of storage devices, accidental damage or deletion, etc. (typically, on a single-drive, single-partition, single-OS system), in which case the ultimate goal is simply to copy all important files from the damaged media to another new drive.
If any of the data files were damaged or lost while being propagated between Usenet servers, users could download parity files and use them to reconstruct the damaged or missing files. Parchive included the construction of small index files (*.par in version 1 and *.par2 in version 2) that do not contain any recovery data.
A tag called "Handler Type" in the original is missing (or rather, moved, see below) in the corrupt file. It has the value "Video track" in the original. The tag called "Handler Description" immediately follows in the original, and is untouched in the corrupt file (value: "VideoHandle"). Later in the corrupt file, the following section appears:
Metadata can be stored either internally, [108] in the same file or structure as the data (this is also called embedded metadata), or externally, in a separate file or field from the described data. A data repository typically stores the metadata detached from the data but can be designed to support embedded metadata approaches.
This applies to files that are corrupt, missing, empty, or that contain superfluous and blatant non-metadata information. [20] This also applies to file description pages that lack a corresponding file or correspond to Commons files and do not include information that is specific to English Wikipedia (like {{ FeaturedPicture }} ).
Data recovery is often performed by specialized commercial services that have developed often proprietary methods to recover data from physically damaged media. Service costs at data recovery labs are usually dependent on type of damage and type of storage medium, as well as the required security or cleanroom procedures.