Everything You Want to Know about Overwrite [MiniTool Wiki]
You probably have heard or seen sentences like this: do not overwrite the lost data if you want the data back! Or if you want to recover lost data, please be careful in case of overwriting! But you might do not know the actual meaning of overwrite, and don’t know why stop doing this or that to prevent overwriting.
So, what is the word overwrite meaning? The word overwrite meaning is that it writes over the deleted data with new data, that’s why the name is. The process of it is writing a set of data (binary) in computer data storage, of course, with new information to replace the previous information. Data that has been overwritten is considering unrecoverable.
The Principle of Overwrite
What’s the difference between delete and overwrite? To understand this better, you should know how data is stored. Digital information is stored in bytes. Each byte contains 8 bits. Each bit has a value, 0 or 1. This way of storing data is called a binary numeral system because it uses two symbols, 0 and 1. Any data stored on a computer is written in binary code, which is a string of 0 and 1.
Each magnet has a plus sign (+) and a minus sign (-), which equals two values, so it is allowed to represent binary code. HDD memory cells or discs contain ferromagnetic surfaces, which are subdivided into small magnetic domains. HDD stores data by directional magnetization of magnetic domains. Each domain can be magnetized in one of the two possible directions, and then represents one of the two values: 0 or 1.
When a file is deleted, the information is not immediately removed from the disk. Instead, the file system simply updates the database and tracks the files on the disk to confirm that the file is no longer needed, then hides the files from being visible.
This information will only be removed if the operating system decides to use this space to store another file. This may be in a few minutes, or weeks, depending on how the computer is used. Until then, data can still be restored by using a data recovery program.
While when you overwrite a file, you tell the operating system not only to update its file records, but also to immediately overwrite disk space with 0 or 1, which makes the magnetic domains on the HDD re-magnetized. This is an irreversible process.
How to Overwrite Data
In computing, there are two primary ways you can overwrite data: overwrite text and overwrite files.
The default behavior of most Word processors is to insert the character where the cursor is, and you can change the standard behavior from insert to overwrite by selecting the original words and then typing.
In insert mode, when you enter new text, the text just displays there. While in overwrite mode, the text you enter will replace the information you selected. Overwrite text simply means that the new characters you type replaces existing characters.
You can also overwrite data by replacing old files with new ones. If you are saving a document with the same filename as an already existing document, then the old document will be overwritten by the new one. So, you must be careful with this since it will cause the old document cannot be recovered anymore. While luckily, the operating system will ask you before overwriting it to make a confirm.
How to Avoid Overwriting
Now you know that when you accidentally delete a file on your computer, the file is actually not removed from the drive. Only that the space it occupies is marked as free. In this case, the deleted file can be recovered as long as you don’t overwrite it. Therefore, in the case of overwriting, we will give you some Tips when you lose important data.
- Do not keep the device running or using.
- Don't search for solutions on the same PC.
- Do not install recovery software on the same drive.
- Do not restore data to the same drive.
- Do not run the built-in recovery CD / DVD.
We hope these tips can help. But you might wonder then what can you do? In fact, you can rescue the deleted data by using a free software.
Other Information about Overwrite
There are theories about the feasibility of restoring erased data. For example, some people say that skilled researchers can restore data by placing your hard disk under an electron microscope to determine the original data, because the coverage is not always completely clean.
It's like erasing a letter with an eraser and writing another letter on it. Sometimes you can still vaguely see the original letter. But none of them has been put into practice. Therefore, there is no evidence showing that the erased data can be recovered
Overwriting is also used for security algorithms. These algorithms use a set of precise rules to remove any part of the original data by writing new raw data. It can ensure data security. If you have data which you’d like to overwrite because you don’t want anyone to find it in any way, you can rely on a top overwriting tool to do this job.