Clearing data (data erasure, data clearing or wiping data) is a software method for deleting data from a hard drive, with the goal of eliminating all traces of data on a magnetic or digital media, to prevent or make it very difficult to recover data, usually in order to preserve confidentiality.
The final data erasure goes beyond the simple file deletion, which simply deletes the pointers to the physical blocks of the hard drive, bytes are always present but not accessible by the operating system.
Unlike degaussing or physical destruction making the media unusable, data erasure destroys information but leaves the media to be used for another purpose, preserving the investment in equipment and the environment.
Information technology handles large volumes of data that a significant part is sensitive in terms of confidentiality. Social security number, credit card number, bank details, medical information and sensitive business data is stored on hard disks of workstations or servers.
They may intentionally or unintentionally be copied onto media such as USB , flash, Zip disk, etc. Many users generally believe that the suppression by controlling the operating system deletes the data, when in fact it does not.
The full and final erasure of magnetic media is not simple because of the persistence of data. In 1996, Peter Gutmann published a study considered a reference on the subject, where he suggests rewriting up to 35 times the deleted areas to prevent forensic data recovery.
It is not disputed that there is trace data even after being crushed, but the recovery technique is very complex.
There are many programs for the complete erasure of a hard drive (hard disk shredders), deleting all data in all sectors of the hard disk. By accessing all sectors, these programs eliminate the risk of data retention.
As opposed to a logical format which erases only the table of contents, this method is called formatting.
Data erasure solutions can be deployed across a network to manage many positions, rather than having to manage sequentially. There are specific solutions for SCSI, SATA drives. Specialized companies also offer data recovery services.
Several government standards or industry standards have emerged for software solutions to secure data deletion. The safety level achieved depends mainly on the number of erasure passes, but also because of the hidden areas of the disk.