Recovering data from a formatted drive is entirely achievable. This article looks into how software is actually capable of data recovery after formatting an internal or external drive and highlights one major setback to how much data can successfully be found.

At the core of this process is the way in which data is stored to drives and deleted from it. Each individual file that you store to a Windows-based FAT format drive (file allocation table) is saved to multiple data clusters on the actual hardware. The FAT file is the crucial file linking your one file to the multiple clusters that store its information.

Formatting, and file deletion for that matter, operates by simply resetting the directory location for the file. In the case of file deletion, the directory is reset to point to the Recycle Bin. Crucially, the process does not however delete the information on the data clusters – these are left intact. The FAT is amended during formatting to show which data clusters are now free to use by the operating system for storing any new data.

Data recovery after formatting a drive consists of checking the FAT for files marked as 'free to use' and scanning the drives for non-empty clusters. Most of the free-ware or low cost recovery tools operate solely on the FAT file and this can generally work well if the FAT has not been corrupted. Even still, due to the importance of this file the operating system always keeps a second copy of it just in case something goes wrong.

Commercial recovery tools will also scan the drive for non-empty data clusters and attempt to which clusters can be formed into individual files. The more high-end the product, the better its algorithms and techniques for recovering files from the clusters alone.

However, the major roadblock to any data recovery will depend on the level of evidence destruction that the formatting application made. Some professional tools are designed to overwrite clusters with nonsensical data in order to completely clear any personal information/files/evidence. If these applications are used then the level of data recovery that is possible will be minimal.

Out of the current batch of data recovery tools on the market, the free-ware applications PhotoRec or Smart Recover are capable of recovering data off of internal drives and flash memory. PhotoRec has a basic user interface but works effectively enough. There are a huge amount of commercial tools to choose from and the one proviso about which to pick is to go for a non-invasive application that clones data during the recovery stage. This is preferable to tools that extract (remove) the data clusters as you would wish to limit the risk of damaging data on adjoining clusters.