Using Diskpart

CommonTater · 10 Apr 2010

Bare Foot Kid said:

Hello everyone.
What I would like is to do is a "secure erase" (write zeroes) to a partition of a HDD before a clean install of Windows 7.

Ok, having looked at the fist part of this thread, I can chip in a little information for you...

Simply this... "Format" is not "Erase"... Even a long format which can take hours to finish is only a surface scan done in READ mode, while this will map bad sectors out of the $Bitmap file in NTFS it will neither fix bad sectors nor erase any pre-existing data.

You will need a 3rd party program to "Zero fill" your drive... Google is your friend... there are lots of them.

However... If you are just doing a clean install, format is plenty good. Yes there's still going to be recoverable data on the drive but that data is neither listed in any directory nor indexed in the Bitmap or MFT records... so as far as windows is concerned it's working on a brand new disk.

The reason old data is not reset to some predetermined value is simply that it's a waste of time. If you had to write zeros on a drive before you could write new data (like they had to do with old magnetic core memory) the process would take *at least* twice as long. With a hard disk you just ignore the old stuff and write over top of it... and that's plenty good enough.

The only time I'd recommend a zero fill is if the drive is leaving your possession with "confidential" data on it... Your financials, medicals or (heaven forbid) something illegal....

ignatzatsonic · 10 Apr 2010

Brink:

Thanks for that clarification.

I guess a person may as well use "clean all" every time rather than "clean" for the sake of security. No harm done other than more time taken.

I gather "full format" is no more secure than "format"?

I assume "Clean all" is the only command available at a prompt in Windows 7 natively that will write zeroes and can write zeroes to C if you boot from the Windows 7 DVD?.

Do "clean all" and "full format" differ significantly in how long either would take to run on a 1 TB drive?

Brink · 10 Apr 2010

Nar, format doesn't actualy erase (write over) the data but just marks them as deleted instead. That's why you may sometimes be able to use a data recovery program to recover data that has been deleted or formatted if it has not been writen over yet.

The Clean all will write over all data on the HDD for a secure erase.

A "full format" (regular format) will do this instead: Differences between a Quick format and a regular format during a "clean" installation of Windows XP

I'm not sure how long it will take, but I would imagine that would take a bit for a 1TB drive to run a "clean all" on.

Tepid · 11 Apr 2010

Yes I have used HDDErase which is the application that calls the internal wipe command of the firmware.
There is no direct route to this command other than using hdderase, and I think a very small (like one other) number of applications that can access this command.

There are some caveates to using it, and yes, you can render a drive useless. Which I have done a couple times. But, if everything goes well, you can be assured that (again, to the best of my knowledge, from the research that I did a couple years ago) all data, including bad sectors are wiped clean.

I have not used it in a long time, but I am pretty sure this Internal Wipe Command is still on every drive sold today.

How to REALLY erase a hard drive - Update | Storage Bits | ZDNet.com

What is Secure Erase?
Secure Erase is built into all ATA-compliant disks drives since 2001. This functionality is recognized by the US Government’s National Institute of Standards and Technologies (NIST) as equivalent to magnetically wiping a drive (degaussing) or physically destroying it. NIST also rates the secure erase commands as more secure than external host-based drive wiping utilities such as Boot and Nuke. Secure Erase complies with HIPAA, Personal Information Protection and Electronic Documents Act (PIPEDA), the Gramm-Leach-Bliley Act (GLBA), and California Senate Bill 1386 for data destruction.

Doing a Zero Fill can be used and is good for the average joe that doesn't really care about wether or not data can be retrieved,but just wants to be secure in the knowledge that most people can't recover the data. Someone getting a hold of a drive that knows what they are doing could still get pieces of data from the drive. Trust me I have researched this.

There are articals out there that talk about even being able to recover data from a shredded drive. Meaning they put the drive through a shredder and grind it down. This is a bit over kill but it has been done according to articles I have read. Or at least theorized. It has been a while since I read anything on this. I did research cause a company I was working for was looking into HIPAA re-certification of HDD's used in the medical field. So they could either resell them or reuse them in other areas of the company. Trust me it is a bigger deal than you think in the medical field for HIPAA among other areas that control sensitive data.

You get hacker eddie that knows how to recover data and a zero wiped drive can give up juicy data.

It all depends on how concerned you are about the data on your drive.

i just put the Internal Wipe command info out here as just that, knowledge, to be taken and researched on further by those interested.

Bare Foot Kid · 11 Apr 2010

I want to thank you all for the information.