Organizations that pay high sensitivity to data safety won’t allow data loss even for once. Thus, how to wipe data thoroughly is closely related to their core interests. For average users, data leakage also needs to be avoided. How do you deal with an eliminated disk? Generally speaking, there are three ways. You can reserve it for future usage, sold it for money back or even throw it. Nevertheless, the latter two ways need you to pay attention. Because you should remove personal information thoroughly in advance, in case that some people may restore the data (photos, videos, accounts and passwords…) saved in that disk by accident.
Generally speaking, computer users choose various ways to deal with their personal information before they abandon a hard disk. And these methods can be summarized as the following list:
Destroy (no revert)
Physical damage or chemical corrosion is the simplest and crudest way to solve the problem of data leakage. However, this method will destroy the whole disk and requires specific environment and equipment.
Deletion is the most common way we use in our daily life to get rid of unwanted data. But data removed by using this method can be recovered effortlessly.
Low level formatting (no revert)
Low level formatting is the most time-consuming method to erase private information completely. It means to wipe and rewrite the cylinders, tracks, sectors and identifying code. This feature is used to initialize a hard disk to shield logical bad track, and is always carried out before hard disks leave the factory. By using low level formatting, all sectors are covered by data flow 00, and all data on the disk will never be recovered.
High level formatting:
There are two forms of high level formatting, i.e. format and quick format.
1. Format (no revert)
Format will clean all data in the disk, generate the information of boot sector, initialize FAT (File Allocation Table), mark logical bad tracks, etc.
2. Quick format (restorable)
Quick format only marks deletion tags in FAT, other than scans the full disk to check bad sectors. By using professional data recover software, there is a possibility to restore data.
Wipe/Clean all (no revert)
Wipe/clean all means to clean all data (files, partitions, partition table, etc.), but won’t change any basic information of cylinders and tracks on the hard disk. This feature is used to wipe data in the disk completely, instead of repair logical bad tracks.
According to the 5220.22-M standard established by USDD (United States Department of Defense), erasing data requires to format and rewrite data for at least three times. For the first time, fully format the hard disk and then write data flow consisting of 0 and 1; for the second time, invert 0 and 1 in data flow and write again; and the last time, write random data stream.
Note: Some people insist Hard disk needs to be erased for at least 7 times to against data restoration, and some even call on 35 times. Let’s have a look at what Peter Gutmann says regarding to this issue:
“If you’re using a drive which uses encoding technology X, you only need to perform the passes specific to X, and you never need to perform all 35 passes. For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do. As the paper says, “A good scrubbing with random data will do about as well as can be expected”. This was true in 1996, and is still true now.”
— Peter Gutmann, Secure Deletion of Data from Magnetic and Solid-State Memory, University of Auckland Department of Computer Science.
Now, let’s talk about how to format and rewrite a hard disk so as to wipe data permanently. Here we would like to recommend a free partition management software, which is named MiniTool Partition Wizard Free. It provides users with five options to wipe a disk completely: fill sectors with Zero, fill sectors with One, fill sectors with Zero & One, DoD 5520.22-M (3 passes), and DoD 5520.28-STD (7 passes).
Below is the operational approach.
Step 1: Launch this program and select the disk that needs to be erased. You can find the option “Wipe Disk” at the left panel or by right clicking the target disk.
Step 2: Click “Wipe Disk” and you will see the following interface. Here are five choices for you to wipe the target disk. What’s the difference? The longer time it requires, the higher security your disk will enjoy. Finally, you need to press “Apply” to execute this change.
Tips: You can also use MiniTool Partition Wizard Free to wipe a specific partition. As the picture shown below, you need to select the target partition and choose “Wipe Partition” to go on. In this way, your private information in that partition will never be restored.