Surely, some of you have heard the phrase “low-level formatting of a hard drive“. In this article, we will explain what it is, when and how to do it.
What does it mean to format a hard drive at low level
First of all, it must be specified that the term “low-level formattingHas changed meaning over the years. Currently, we refer to the operation called “Zero Fill, But in practice the purpose is always the same, that is to erase the contents of a hard disk in such a way that it is unrecoverable.
This practice is useful in the case of classic, magnetic hard drives, while it is better not to use it for SSD, since they handle data differently and you will only shorten their life. If, for example, you intend to sell your PC and want to be sure that all your data cannot be recovered, surely low-level formatting is recommended.
A hard disk, whether it is a magnetic disk or an SSD, even if obviously in a different way, is divided into areas and sectors, which define the rules by which the data will be stored. From a certain point of view, you can imagine a disk like a warehouse shed. Before being used, this shed is organized, all the various shelves are positioned and labels are placed to define the different aisles. In this way, when a box is stored, a certain order will be followed, so that it can later be easily retrieved. The same is true for the PC, except that instead of a box there is a datum.
These rules are contained in the file system. When you format a disk normally, ie do a quick format, you are not actually erasing the data, but you are telling the computer that that disk is empty and can be used to store new data. When you do a quick format, you can imagine a hard disk full of data like a book of which you only delete the index. The data in the various pages are always present, but without the index the PC is unable to retrieve the information. However, since the data is still physically available, there is the possibility to retrieve and read it if desired, even if it is not an operation within everyone’s reach. To make sure you make your data unreadable, you need to physically delete it and not just delete the index.
Low-level formatting, also called “Zero Fill“, or “Write Zero, Consists in going to fill the whole disk with zeros. In fact, the data are stored in the various sectors in the form of “1” and “0” (binary language). By replacing all the data with zeros, it means in practice to make them unreadable, since they have been physically replaced by other values. Returning to the example of the book, it is as if all the letters were replaced with the letter “A”. It is clear that in this case the book would be totally illegible and the information contained in it completely lost.
This practice can be considered safe, and unless you have state secrets on your disks and are closely monitored by the NSA, you can rest assured that you won’t need anything more. But how to do a formatting of this type?
How to do low-level formatting
Windows 10and all Windows versions from View onwards, they perform a real format, filling all sectors with “0”. You just need to make sure you don’t select Quick Format from the menu. If you remove the check, in addition to eliminating the famous “index”, a check will also be made for bad sectors, which will be marked as unusable in order to prevent possible data loss, in addition to the fact that the disk will be completely overwritten with zeros.
Therefore you don’t need complicated tools or commands: use Windows formatting, uncheck “quick format” and everything will go well.
