If you delete a file and empty the trash, the file can’t be accessed, right? Not so fast. In this article, we’ll explain how deleting files work in operating systems, how deleted files can be reconstructed, and how to securely erase your files to the point of no return.
How Do Operating Systems Delete Files?
When you delete a file, it first goes into a special directory, called the Recycle Bin, Trash, or other names depending on your operating system. This ensures that if the file is deleted accidentally, it can be restored immediately.
If you decided to empty the trash, the system handles the request in a seemingly unconventional way. It only removes the reference about this file in the file table. The file is gone (at least according to the system), and the system can write new data on the location, but the data is still there.
Why can this happen? It is much faster to delete the index than to overwrite the whole file, especially if the file is too large. Moreover, overwriting files right away can cause additional wear and tear, especially if you delete files very often. Besides, if the file is removed unintentionally, it can still be restored using data recovery software.
How Does Data Recovery Software Work?
At this point, you might be curious how data recovery software can somehow reconstruct pieces of the files, even after the location of the file is not available.
If your files are fragmented, the app uses complex algorithms to look for known patterns, revealing file formats, or even the beginning or end of the file. After that, it tries to reorganize any recoverable data using recognition systems. It’s like completing a challenging puzzle in which pieces from different photos are spread out but can be moved in the right place using some sophisticated algorithms. This process is file carving, and it does not guarantee complete recovery of your data.
If it is not fragmented, things are much more straightforward. They simply search for headers, footers, and evidence of file types, reconstructing a file quite quickly.
Safely Recovering a File After Accidental Deletion
First and foremost, shut down your computer the moment you realize some important files are deleted. The more time has elapsed since the removal of the file, the less likely that the file can be recovered.
Then, go through your file recovery options. Make sure you have backups where the file is still intact. If there are no backups available for any of your files, start backing up immediately after the files have been restored. You never know when data loss will occur again.
If the file can’t be restored with a backup, try to install a data recovery app. However, the process of simply installing an app might overwrite your deleted files, thus making them unrecoverable. Therefore, running it with a removable storage device is an excellent option, assuming you didn’t delete files there.
If the hard drive has sustained any physical damage, send your storage device to a professional data recovery center right away. Like other hardware problems, you can’t fix them with software.
Erasing Files Securely
To make files unrecoverable, you have to overwrite them with new data, and you may have to overwrite the entire drive, depending on the tools you have. As a result, it’s best to back up all crucial data to other storage devices before wiping the drive.
Another method is cryptographic erasure. It means encrypting your drive and deleting the key. This renders the information in the storage device unreadable, and the process is faster than overwriting your entire drive.
In some cases where data needs to disappear right away, physically destroying the storage device is an option. If done properly, this ensures that no traces of your data can be found, even with the most complicated and professional algorithms.
Think Before You Post!
Aside from retaining and removing confidential files on your computer, there is one thing that you have to pay more attention to. Think before you post online! Once online, the information will likely be online forever because there is virtually no way to completely erase all copies, especially in social media.
If a comment, post, or anything else goes online, someone might reach the information, take screenshots, and/or share or quote them using social media or on their website. Moreover, employers search you online when considering whether to hire you or not. If they found offensive content, it will be a huge negative factor. Furthermore, if bad people were to access your messaging app or “secret” posts, they might force you to pay the ransom, or the content will be shared and/or sold online. Either way, embarrassing or inappropriate things that you posted online, even if deleted, might harm you at any time.
Remember that when your files are permanently deleted, the data is still there. Thus, if you really have to get rid of the information and prevent recovery, use some software to erase your drive, or just refrain from creating this file beforehand.
References and Credits
- Computer Hope. (2018, January 24). When I delete a file on my computer, where does it go? Retrieved August 6, 2021, from https://www.computerhope.com/issues/ch001463.htm
- Top Ten Reviews Contributor. (2020, September 4). How does PC data recovery software work? Retrieved August 6, 2021, from https://www.toptenreviews.com/how-does-data-recovery-software-work
- Darcy French. (2020, June 8). How data recovery software works. Retrieved August 6, 2021, from https://www.techradar.com/news/how-data-recovery-software-works
- William Elcock, Andrey Vasilyev. (2021, June 7). What is Data Recovery & How Does Data Recovery Software Work (2021). Retrieved August 6, 2021, from https://www.handyrecovery.com/what-is-data-recovery-and-how-does-data-recovery-software-work/
- (n.d.). File carving methods in data recovery. Retrieved August 6, 2021, from https://www.klennet.com/carver/carving-methods.aspx