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Specifically, I am long-formatting to ExFAT.
Is this filling my external HDD with zeros?
If not, how can I do this with a 230GB SATA hard drive in an external USB caddy?
user1083734
Posted 2012-02-25T12:20:41.237
Reputation: 219
Does long-format in Windows zero-write the hard drive?
Answers
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If you're running Windows Vista or newer, then yes.
http://support.microsoft.com/kb/941961
That KB article details the changes with the format command starting with Vista, a long format now writes zeros to the entire drive. Previous versions did a read only check of every sector.
afrazier
Posted 2012-02-25T12:20:41.237
Reputation: 21 316
0
For Windows XP, No, the "long" or "regular" format is just checking the sectors for consistency. When the files get erased, only the file tables are erased. The files remains are still recoverable with unerase file utilities. Here's Microsoft's explanation. What you want to use is a utility that performs a "kill disk". One good tool that has a 1 pass freeware version is Active@, but there are many others if you do a search. (1 pass means it writes 0's to each sector making those file remains.) Writing over USB to a 230gb drive will take many hours and is an overnight task.
jdh
Posted 2012-02-25T12:20:41.237
Reputation: 6 645
Did you manage to get round to testing this, @Moab? – Hashim – 2017-08-08T23:41:15.860
@Hashim, no reason to test it is a documented fact. – Moab – 2018-04-04T22:41:46.430
Your own words: “I don’t like assumptions even when they are obvious, I guess I will test it soon.” If it is a documented fact, as you say, that the GUI Windows’ format tool writes zeroes to disks, where is this documentation, as I’ve been unable to locate it yet. – Hashim – 2018-04-04T22:50:09.023
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@Hashim: See https://superuser.com/a/1046139/34636. Someone actually went and tested the Windows 7 GUI. The underlying APIs are not well documented anywhere, and the KB Article in my answer is the best and most authoritative information on the subject I'm aware of, despite it being user-centric rather than developer-centric.
Any MS supported, documented method of formatting a disk is going to write zeros to the volume when told to do a full format in Vista or later.
@afrazier Wow, nice find. You're right about the less superficial workings of Windows being badly documented, I found the same thing when looking deeper into the Registry. Thanks for the link, and your help. – Hashim – 2018-04-05T02:53:15.703
I have always wondered if it only writes zero's when using the command prompt, I cannot find documentation where it says it does overwrite when formatting in explorer, disk management or from an Vista or W7 install dvd. The document specifically shows it done from the command prompt and using diskpart. – Moab – 2012-02-25T17:30:01.757
@Moab: I'd guess that the underlying system calls are the same from cli and gui, so it doesn't matter. – afrazier – 2012-02-25T18:26:29.847
I don't like assumptions even when they are obvious, I guess I will test it soon. – Moab – 2012-02-25T18:31:48.607
With ImDisk and some small in memory volumes, it should be relatively easy to test. – afrazier – 2012-02-25T18:41:50.233
I have a small utility to watch the read writes on any drive in my system, so I will just connect a small usb hard drive and long format it. – Moab – 2012-02-25T18:45:17.140