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Using SysInternal’s SDelete app

SDelete is a Vital utility to any Windows. Ironically, only about 1% of Microsoft Windows Users even know about SDelete.

Microsoft decided long ago, that it was “better” to remove only a files entry in the MFT (Master File Table) when a file is “deleted”, rather than actually removing the file, by over-writing it with Zeros.

So basically. In Windows, when a file is deleted, the file is still there.  Yes even if You  “permanently delete” from the Recycle Bin, it is still there.

This creates 2 Problems.

  1. User data can be “mined” from the system when the OS is not in control. Think data recovery Software, and “undelete” Apps.
  2. Software outside the OS, CANNOT correctly distinguish free space from data after a certain amount of files have been created/deleted. Think guest file system inside a virtual machine.

Regardless of the which reason, SDelete is Your friend.

In the Example below I have downloaded SDelete from Here<—– Official Microsoft Technet site.


Official Microsoft Technet Download Page Screenshot

Now extract the contents of the Zip file directly to the C:\ Drive.

SDelete does not have a gui, so You will have to use an Old School Command Prompt. Start–>Run—>Type “command”—->Hit Enter

If You are using Sdelete  for virtual disk image optimization, simply run the following command “sdelete -z c:” without the quotes.

This will make 1 pass (-p 1) and write Zeros to all the free space (-z) on drive C:\

sdelete -z c:

sdelete -z c:

If You want Sdelete to securely erase “free” space after deleting files, run the following command.  “sdelete -c -p 1 c:”  Once again without the quotes.

Once You hit enter, Have a doughnut they are good.

NOTE: This process can be painfully slow on the following:

  • Huge Raid arrays
  • Slow Hard drives USB HDD, Laptop HDD, older Pen Drives
  • Virtual machines
  • If You used the -c option.
  • Grandma’s Old E-Machine

Once SDelete has done its thing, You should see something similar to the message below.

sdelete completed.

SDelete completed

Have Fun.

One thought on “Using SysInternal’s SDelete app

  1. Pingback: Compress KVM / Qemu Disk Image the Easy Way, and Reclaim Your free space! | Geek Industries

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