Complete deletion of a hard disc

koilada

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I' m going to sell a hard disc, so I need to make a complete deletion so that buyer won't be able to restore any data from it.
Is there any way?
 

juanrdp

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Thats the normal clean (and its not enought to avoid the recovering of the data), the clean all also have each and every disk sector on the HDD written over and zeroed out completely to securely delete all data on the disk to help prevent the data from being able to be recovered.

But that's correct, the clean all would be enought.
 

koilada

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Forgot to say that there's no OS in this disc, just stogare.
I use Win 7-64.
So, do I use that DiskPart of that link? All 13 steps?...
Is there something more simple? :)
 

steven_15

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Think of a hard drive like carbon paper. You write on it and it leaves an impression on whatever is below. Formating is like removing that carbon paper and throwing it away. The impression is still on whatever is below AND someone can dig in the trash and get the carbon paper out.

Secure erase programs overwrite everything on the drive, the really secure ones do so 2-47 times (yes, really).

It's a very simple process unless you accidently point it at the wrong drive, it just takes a while (days, for the slowest most secure erases).

https://www.lifewire.com/eraser-review-2619133
 

koilada

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Think of a hard drive like carbon paper. You write on it and it leaves an impression on whatever is below. Formating is like removing that carbon paper and throwing it away. The impression is still on whatever is below AND someone can dig in the trash and get the carbon paper out.

But this someone must be a pro, right? I guess not anybody can dig deeply.


It's a very simple process unless you accidently point it at the wrong drive, it just takes a while (days, for the slowest most secure erases).

https://www.lifewire.com/eraser-review-2619133

I 'll use that Eraser and hope its indeed simple. Thanks:)

Do such programs wear the discs?
 

rkzhao

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Pro/Superman.

Even in Gutmann's original paper about it, data recover was only theoretically possible because there was a greater than 50% chance of determining the right value for the overwritten bit. Also consider that the original theory was for drive technology in the late 90s and pretty much everyone agrees (including Gutmann himself iirc) that with modern drives, there's no need to run tens of overwrites.

Still, peace of mind is nice and people are paranoid about things they don't understand.



The nice thing is that erasing a HDD is fairly easy, just time consuming if you want to run multiple passes. Really, at it's core, all any of these erase methods do is overwrite the entire disk with new data. The differences just lie in what kind of specific bit values they use.

That does mean you are writing an entire drive's worth of data every pass. So there is of course going to be some wear. With HDDs, the wear is probably not too much of a concern. For SSDs, where there is a somewhat hard limit in how much write and erase cycles the drive can take, this is more of a concern.
 

steven_15

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If all you do is delete or format, recovering isn't very hard. There's at least as many file recovery programs as secure erase programs if not more and if it's not overwritten by something else you can bring everything back with a few clicks. If you use a secure erase program recovery is a lot harder or even impossible. If it's an SSD instead of a mechanical disk, conventional file recovery won't work because TRIM will automatically release deleted files after a few minutes. There are professional tools that can still find it but your buyer most likely doesn't have those and unless you are a known employee in some highly classified field they probably won't care about your personal files anyways.
 

koilada

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The disc is not SSD. Of course data are many times overwritten, exept the recent ones. Recent ones are only videos.
Suppose its 300GB of videos (mpeg, wmv, avi etc). After a format someone can recover all these 300GB of working videos?
 

rkzhao

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A format only deletes the file system. Essentially, it marks the disk as unused without overwriting the existing data. The actual data is still on disk. Similarly, when you just delete a file through windows, the actual data is still on disk. That data is only gone when it is overwritten by something else.

That's why there are "secure erase" applications like DBAN which "erases" the disk by actually overwriting the entire surface with junk data.

With older disks, there is still enough residual signature after a single overwrite to possibly determine what the previous data was. Think of it kind of like erasing something you wrote in pencil on paper. There is still a slight imprint left for someone to possible make out what you erased. So someone can still in theory, go through the data bit by bit and determine what was written before. That's where the idea of multiple overwrites to have a more fully secure erase came from.

With modern drives, that is not really needed, or at least, not to the same degree.
 

koilada

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if I delete those 300GB and then save another 300GB of something else then delete, the videos will be still working? I mean overwriting once, is enough?

 

koilada

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So, one deletion is enough? The second set can be something unimportant.

Another query: cut-paste a file from a disc to another disc can do the job?
 

koilada

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If I overwrite the whole capacity of disc, do I cover those specific 300GB?
I think the secure erase program is not good idea if this going to wear disc.

What about my other question? Cut-paste a file leaves no trace?
 

Zkye

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Don't worry about the wear on a HDD. It's insignificant. Do one pass (one full write) with a secure erase program and that's it. Writing it yourself does the same amount of wear.

Cut works just like delete, but instead of sending the file to the Recycle Bin, it will copy it where you paste it.
 

koilada

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I 'll transfer the files anywise.
So you tell me that cut-paste leaves no trace? Then there is no reason to use a secure erase program, right?
 

Zkye

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No. I'm saying that that cut-paste is just as useless as deleting the files. There's free software that can be used to recover them.
 

koilada

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Deleting a file leaves a trace in the local disc(recoverable data). Cut-paste a file to another pc leaves trace too?

If in cut-paste there is no recycle.bin, how would someone recover?