7

According to this article from Microsoft, zeros are written to an entire disk when it is formatted (not using the quick format option) in Windows Vista and newer versions of Windows. My question is the following:

Does this also apply to Windows 7? The above article from Microsoft does not specify Windows 7 under "Applies to", although Windows 7 is (to the best of my knowledge) a later version?

  • Updated my answer with proof of this being the case. – Jonno Mar 1 '16 at 12:53
  • This is not just to verify read/write, some people might have argued that this is what they expected was to occur - protection against data recovery was expected. Zeroing flash memory makes later recovery of lost data a lot easier as well. – mckenzm Dec 28 '18 at 1:09
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Yes, in the case of versions of Windows after Vista.

Prior to Windows Vista, a full format was the same as a quick format, but included a disk scan for bad sectors. As of Vista, this scan was replaced by writing zeroes to each sector of the drive (which in turn would reveal any bad sectors that couldn't be written to).

Another source here related definitively to Windows 7 states:

What's a quick format?

Quick format is a formatting option that creates a new file table on a hard disk but does not fully overwrite or erase the disk. A quick format is much faster than a normal format, which fully erases any existing data on the hard disk.

Emphasis mine

I don't know why the source you've provided isn't mentioning Windows 7, but it does apply.

Evidence

Prior to formatting my SD card:

enter image description here

Full format complete:

enter image description here

After formatting my SD card:

enter image description here

  • Thanks for the reply. Could anyone confirm that it actually works in practice? I.e. that a disk is in fact overwritten with zeros when it's formatted in Windows 7? – user49897 Feb 29 '16 at 5:56
  • To zero the drive using format requires it be done from the command line...support.microsoft.com/en-us/kb/941961 – Moab Feb 29 '16 at 22:31
  • 2
    @Moab I'm not sure the source means only for the command line. It even says that the Windows Explorer: Click to select the Perform a quick format check box. is the same command as Command line: Use the format /q command. - implying they operate in the same way. Have posted evidence that the GUI does zero the drive. – Jonno Mar 1 '16 at 12:50
  • @user49897 Proof added using HxD to view the drive contents. – Jonno Mar 1 '16 at 12:50

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