Recovering data from a formatted drive is often easier than you might think. This post looks at how software can recover data from a hard disk drive that has been formatted or had data deleted from it.
Fundamental to the whole data recovery process is the way in which the data is written to the drive and deleted from it. Every file and folder that is created on a Windows based FAT32 formatted drive is saved to multiple data clusters across the hard disk. The location of these clusters that make up the file is stored to a central repository known as the File Allocation Table or FAT. The FAT entries are therefore crucial in linking your file together.
Both format and delete operations work by resetting the entries for that file in the File Allocation Table. In the case of file deletion, the directory is reset to point at the Windows Recycle Bin. Crucially, this process does not delete the information in the data clusters which hold your data – these are left intact and untouched. 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.
Retrieving data from a formatted drive consists of checking the FAT for files marked as ‘free to use’ and scanning the drives for non-empty clusters. Most software recovery tools operate entirely on the FAT file and this can generally work well if it 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.
Quality data recovery software tools will also scan the drive for non-empty data clusters and attempt to determine which clusters can be formed into individual files. Often the software with the best search and recovery algorithms are also able to restore files from the clusters alone.
Problems in recovering the data can sometimes arise if a third party software program has been used to format or delete data. In addition to resetting the FAT entries, these programs will often overwrite the data clusters too making recovering impossible because the data you wish to recover in no longer there.
Is it really necessary to buy a software recovery program? These days it probably isn’t as there are many online data recovery services available that can dial into your system over the internet and recover the data for you remotely. There are two big benefits to this – it’s often cheaper than buying a software tool and the people at the data recovery companies will have recovered data remotely many times before and know what they are doing.