Wipe a computer hard drive completely

Learn how to completely wipe your hard disk data

Formating a hard disk will not delete your private data for ever, it actually only deletes the address tables of the hard disk. Special forensic tools will still be able to undelete it and recover most of the old data. This makes you vulnerable to data theft and privacy invasion.

Even after a hard drive format your data will still be recoverable and open to identity thief. Formatting a hard disk does not overwrite the data, it simply makes the hard disk available to reinstall the operating system but the old data is still stored underneath.

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Identity thieves love second hand computers and hard drives because they know that can get credit cards, emails, passwords and usernames out of the average hard drive.

To be safe while selling or giving away your second hand computer, you will need to digitally shred these personal files permanently.

Only a secure overwritting using the US Department of Defense (DoD 5220.22-M)) recommendations of wiping data either 3 times or 7 times, will guarantee you that data can not be recovered, not even by specialist computer forensics hardware.

A good disk wiping application will overwrite the master boot record, partition table, and every sector of the hard drive. Disk wiping algorithms differ from product to product, normally, you will need to reformat the hard drive after wiping it completely.

Complete disk wiping

Completely wipe your hard disk

The best way to make sure your hard disk data will be wiped for ever is to use some tool such as DBAN to overwrite everything for up to thirty five times, although the standard Department of Defense DoD method is good enough for high security.

Overwriting a hard disk can be very time consuming. The speed will depend on your hardware, mainly the computer unit processor, and the size of the hard disk to be wiped.

As a guide, a 1 terabyte hard disk securely wiped using DBAN on a double core intel E5200 processor being overwritten with the DoD method, will take a couple of days.

DBAN is a live CD that will securely overwrite the contents of any hard disk that it can detect, it is ideal for emergency data destruction.

How many times should I overwrite data?

Learn how many times you should overwrite data

False myth about wiping data

It is an extended myth that the more times you overwrite a hard disk the harder it is to recover data from it. This was true for old computers, but because new hard disks store data diferently, overwritting it 7 times will not make it safer than overwritting the hard disk 35 times (Guttman method).

Most likely you will only need to overwrite your data 3 times to make it irrecoverable.

Free software to wipe your hard disk:

Secure Erase: DOS based utility that sanitizes all data on ATA hard drives. It works from a bootable live CD or USB pendrive. No longer developed.

Copy Wipe: It works from a bootable CD, freeware utility for securely overwriting (wiping/erasing) entire hard drives. No longer developed.

DBAN: A live CD that can wipe any operating system, it will load after booting up your computer by changing BIOS settings, after which you will be given a choice of data wiping algorithms to securely erase the whole hard disk.

DOD-5220, implemented by the US military, varies depending on the security classification of the data to be erased. Should the data be classified confidential, three random passes are required.

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DBAN wiping hard drive

Darik's Boot And Nuke wiping hard drive