Data Remanence - Definition

Data remanence is defined as the residual data remaining on some sort of object after the data has been deleted or erased.

The problem related to data remanence is that there may be some physical characteristics of that data remaining on the media even after we've tried to securely erase it. Depending on the value of the data, it may be very important to securely erase the data so that there are no residual characteristics remaining that may allow anyone to recover the information.

On a typical hard disk drive (HDD), the data is represented onto the hard drive by using magnetic technology. In other words, the zeroes and the ones are represented by using magnetic technology. This type of technology can be used to re-record new data onto the drive as we can alter the magnetic field so that we can overwrite and erase any data that may have been represented onto the data previously.

Solid-state drive (SSD) technology, which is newer technology, does not use magnetic fields to represent the information, instead, it uses flash memory to store data.

Flash technology uses electrons that change the electronic "charge" in a "flash" to represent the information. That is why it is called "flash" technology. Flash memory, such as SSD, does not require power as moving parts are not required to access any stored data.

Data remaining on media that use magnetic technologies, such as HDDs, become an issue if the value of the data that was stored on that media is high. Since there may be methods to recover the original data, sanitizing the information must be done effectively by using secure methods.