[accesscomp] Dan's Tip for today

  • From: "Bob Acosta" <boacosta@xxxxxxxxxxx>
  • To: "Bob Acosta" <boacosta@xxxxxxxxxxx>
  • Date: Thu, 26 Jul 2012 07:26:24 -0700

    Easy Way to Securely Erase a Drive

Updated 17. July 2012 - 2:15 by v.laurie

when you want to really erase them. There are various programs available to 
wipe everything off a drive and Gizmo's has a selection of free ones at this 


But Windows also has a feature for securely erasing drives built right in 
with no need for anything extra.

It is a little-known command line tool called Cipher.exe. The tool has been 
around for a while and is used mainly for managing the Encrypted File System 
(EFS). However, it has a switch that provides for the over-writing of all 
free space on a drive with a random sequence of 1's and 0's. The syntax of 
the command is a little quirky and is frequently misunderstood in web 
articles. One peculiarity is that the Microsoft instructions seem to specify 
that you have to designate a folder and then all the free space on the drive 
that contains the folder will be over-written. The reason for including a 
folder in the syntax seems to be so that folders mounted as volumes are 
included. Here is the procedure to securely erase deleted files from a 
volume X:\

1.    Use the usual procedure to delete everything that is to be wiped off 
the drive X:\. Deleted files are actually still there in the free space so 
the next step is to write over the free space with the Cipher command.

2.    Open a command prompt with elevated privileges.(This previous tip 
explains how.)


3.    Enter the command cipher /w:X:\Somefolder

4.    Somefolder can be any folder that hasn't been deleted. Unless the 
folder has been mounted as a drive, it isn't affected.

5.    Cipher will then write random bits all over the free space. It does 
three passes. It does not affect files that have not been deleted. Be aware 
that this could take hours for a large drive and might best be done 
overnight. Like a lot of Microsoft tools, it seems to be rather slow.

The syntax given in step 3 is taken from the Microsoft description (link 


and is repeated elsewhere. Whatever the Microsoft documentation may say, 
having to specify some arbitrary folder made no sense to me. So I tried 
cipher /w:X:\  (without designating a folder) on USB keys in Windows 7 and 
it seemed to work. Your experience may differ.

The Cipher command is available in most currently used Windows systems but 
not Windows XP Home.

If you wish to clean an entire volume, there is a second command-line option 
in Windows Vista/7. There is a switch for the Format command that zeroes all 
sectors. It is:
    format X: /p

This will zero sectors once. To do n passes, the command is:
   format X: /p:n

This is a full format and differs from Cipher in that it removes everything, 
not just deleted files. It may take a long time. The actual command you use 

involve  additional switches that can be found in the article regarding 
switches shown below.


If you want to safely erase the entire system, including Windows, then a 
third-party tool like DBAN that operates from an external disk is needed. 
DBAN is a free download at this link.


Other options are discussed at Gizmo's Best Secure Erase Utility


Dan Thompson
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Robert Acosta, President
Helping Hands for the Blind
Email: boacosta@xxxxxxxxxxx
Web Site: www.helpinghands4theblind.org

You can assist Helping Hands for the Blind by donating your used computers to 
us. If you have a blind friend in need of a computer, please mail us at the 
above address.

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