Question Best way to clear harddrives

[T2urtle]

Hi all,

I'm getting ready to sell a few laptops and desktops. Aside from formating the HD 3 times, any other way of protecting myself? The last thing I want is to have some guy find a way to recover my stuff and take the little money that I have.

I'm not paranoid, I just want to make sure I can do what I can prior to selling. These are normal spinning disk drives.

 

[razel]

You don't need to format the drive 3 times. Once is fine and you can do it via Windows. Get the disk down to one partition and when you format, uncheck the 'quick format' checkbox'. You can even just use diskpart's 'clean all' command.

You can also use secure erase if the HDD manufacturer provides tools to do so.

 

[Shmee]

Make a toolset / linux boot disc / USB, boot it and use the dd command to write 0's or randoms. There are bootcds and programs that include this as a feature, making it easy. I like parted magic for this, but the later versions are no longer free.

 

[Fallen Kell]

I would not rely on formating a hard drive to wipe the data, even more so if the drive is a SSD (which are typically copy-on-write, meaning any files that get modified are simply written to a new block on the drive and the old block is simply marked as free to reuse). SSDs also typically have an overprovisioning of storage in order to deal with wearing out of the cells. For most SSDs the drive manufacturer will typically have a utility that will properly wipe it. For drives that do not, I would use linux and use the dd command to write 0's to the entire drive 2 times (since it should in theory write over the reserve/overprovisioning area starting on the second time through). Again, not something you need to worry about since you have regular hard drives.

There are also tools out there designed specifically for this, such as sdelete in windows (which you can use to fill a drive with zero's), or a bootable CD/DVD/USB called DBAN (Darik's Boot and Nuke).DBAN was for traditional hard drives. I also seem to recall a program called scrub. Again, most of these were for non-SSD based disks.

 

[mikeymikec]

You don't need to format the drive 3 times. Once is fine and you can do it via Windows. Get the disk down to one partition and when you format, uncheck the 'quick format' checkbox'. You can even just use diskpart's 'clean all' command.

You can also use secure erase if the HDD manufacturer provides tools to do so.

I downvoted this because it's mostly incorrect. Quick formatting and diskpart clean erases a tiny amount of information from the drive, such a pointlessly small amount that anyone actually interested (armed with some data recovery software) in recovering data would not be severely inconvenienced by this strategy.

The secure erase advice isn't so bad, but it would depend on the quality of the software any given manufacturer provides.

 

[VirtualLarry]

I downvoted this because it's mostly incorrect. Quick formatting and diskpart clean erases a tiny amount of information from the drive, such a pointlessly small amount that anyone actually interested (armed with some data recovery software) in recovering data would not be severely inconvenienced by this strategy.

The secure erase advice isn't so bad, but it would depend on the quality of the software any given manufacturer provides.

Well, "CLEAN ALL" rather than just "CLEAN" will zero all (host-visible) sectors out.

Also, "Secure Erase" doesn't depend on the software, it depends on the device itself. (ATA Secure Erase command)

 

[mxnerd]

35 Free Programs to Completely Wipe Data From Hard Drives

Here are several free data destruction software programs, also called disk wipe software or hard drive eraser software. Last updated September 2022.

www.lifewire.com

 

[mikeymikec]

Well, "CLEAN ALL" rather than just "CLEAN" will zero all (host-visible) sectors out.

Also, "Secure Erase" doesn't depend on the software, it depends on the device itself. (ATA Secure Erase command)

Yep, looks like you're right about 'clean all', I stand corrected!

 

[bononos]

Would zeroing the first 100Mb (instead of the whole disk) be enough to securely erase the partition table. Recovery software could still trawl through the disk but it would probably take much longer to find anything interesting.

 

[mikeymikec]

Would zeroing the first 100Mb (instead of the whole disk) be enough to securely erase the partition table. Recovery software could still trawl through the disk but it would probably take much longer to find anything interesting.

The thing is, who'd bother trying to recover data from a second-hand drive they just bought? At the end of the day, if I were so inclined I'd just set the recovery software off (5-10 minutes' work?), come back say 8 hours later and see what it found. So for those who know how, provided they have the time and inclination, why not.

I've always got around this problem by either physically destroying the drives I want to get rid of or by giving/selling them to people whom I know wouldn't bother wasting their time. At the end of the day on the heck of a lot of peoples' drives they're going to find nothing particularly interesting anyway. Sometimes when I'm going through old drives that I've taken from customers' old computers, I'd try to figure out whose drive it was, and even going through say the Documents/Downloads folders on an intact file system I still have no idea whom it belonged to originally, and not because they took the time to 'delete' a few files first.

If you're selling the drive to someone you don't know and the drive did contain sensitive data then I guess you have to assume that they're the kind of person who'd happily trawl through your garbage, which is pretty much what this situation amounts to IMO.

 

[Fallen Kell]

Would zeroing the first 100Mb (instead of the whole disk) be enough to securely erase the partition table. Recovery software could still trawl through the disk but it would probably take much longer to find anything interesting.

No. It is trivially easy to restore data from a disk that has simply had the partition table and beginning of the file system deleted. Most file systems have multiple backup file tables which can be accessed to find the location data of files on the disk and recover the files and data. You need to perform a complete wipe by zero filling the entire disk.

The exception to this is if your filesystem is an encrypted one, but even then I would still just wipe it (it is not that hard, just kick it off overnight and it will most likely be done in the morning).

 

[Billy Tallis]

Would zeroing the first 100Mb (instead of the whole disk) be enough to securely erase the partition table.

GPT puts a backup copy of the partition table at the end of the disk.

(This is occasionally a source of confusion when someone tries to image one drive onto a larger drive and then resize the last partition, without first updating the GPT to account for the new drive capacity.)

 

[dlerious]

I used to use Eraser for software or a magnetic degausser for spinners.