Data Recovery Algorithms

Engineers and developers from Hetman Software worked out a unique data recovery algorithm that combines content files search with data from the tables and their copies saved on a hard drive.

Michael Miroshnichenko
Full Name: Michael Miroshnichenko
Age: 31 years
Position: Software Developer
  • There are almost as many algorithms for recovering data as there are tools. Can you tell if some are better than others?
  • Indeed, there are many recovery tools on the market. However, most are based on similar principles. Trade names create the impression of variety, but in fact there are just two major methods used by these tools.
  • The first method is based on scanning the file system looking for recoverable files. Being the oldest algorithm, it was used long ago in tools such as “undelete”. While this method is old and simple, it still serves its purpose, allowing to recover many types of files that cannot be recovered by the more sophisticated signature search method. There are no limitations on the type of file or disk fragmentation. However, this method has a major drawback: it can only work if there is a working file system, and if the file system contains information about a particular file. If the disk has been formatted, or the file system itself is damaged, this method will be completely useless. This brings us to the more recent development, a family of signature-search algorithms.
  • Data recovery algorithms based on signature search scan the entire disk (and not just a file system) looking for known types of files based on their characteristic signatures. In a sense, this is similar to how antivirus programs operate. The moment they see a familiar signature, they can find the file’s header, parse information and calculate the effective location and length of the file. Bingo, it’s done.
  • However, signature-search has its drawbacks, too. Namely, it is limited to a certain subset of file types featuring characteristic signatures (many files don’t). Also, this algorithm cannot correctly recover fragmented files: only the first segment will be recovered, followed by random data.
  • Finally, today’s tools such as Hetman Partition Recovery can scan the entire disk looking for current, abandoned or incomplete file systems and using that information to recover files. This allows recovering much more information than by using any single algorithm alone.

Recommended Products

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