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Preparing hard drives for sale


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#1 Scooterspal

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Posted 28 February 2018 - 07:18 AM

Hello and thanks for any help you can provide me.

 

I have a set of 4T hard drives that I no longer need. Each is full of material, none of it confidential. I want to put them up for sale but do not want to have to do a full format to wipe them clean.

 

Is there another way to prepare these drives so that the new owner cannot access the material but not have do to a full 48 hour format?

 

Thanks!


Edited by hamluis, 28 February 2018 - 09:19 AM.
Moved from Internal Hardware to Backup/Imaging, etc. - Hamluis.


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#2 Allan

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Posted 28 February 2018 - 07:25 AM

If the data is not confidential or sensitive you can do a "quick" format of each drive. If the new owner wants to use a third party utility to recover the data he or she will likely be able to do so, but absent that the drives will be empty.



#3 Platypus

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Posted 28 February 2018 - 07:27 AM

The minimum requirement to completely prevent access to the contents of the data area, but leave the drive operational is a zero fill. I haven't zero-filled a 4TB drive so I can't predict just how long it would take.

 

Edit: Obviously Allan & I cross posted.


Edited by Platypus, 28 February 2018 - 07:27 AM.

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#4 OldPhil

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Posted 28 February 2018 - 07:36 AM

IMO the quick format in your case should be sufficient due to you description. Does anyone think someone would spend the $$$ to retrieve data that would be irrelevant to them?

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#5 Platypus

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Posted 28 February 2018 - 07:45 AM

In most cases that would be right, someone wants a drive to put their own stuff onto, rather than to hunt down what someone else may or may not have had on the drive previously.


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#6 Allan

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Posted 28 February 2018 - 08:04 AM

IMO the quick format in your case should be sufficient due to you description. Does anyone think someone would spend the $$$ to retrieve data that would be irrelevant to them?

 

Just to be clear, one does not have to spend money to retrieve data after a format (quick or full). All a format does is erase the pointers, making it impossible for the MFT to locate the file(s). The result is a seemingly empty drive. There are many readily available utilities that can rebuild the structure or find specific files. Having said that, if the data is unimportant then a format (quick OR full) is more than sufficient.


Edited by Allan, 28 February 2018 - 09:05 AM.


#7 britechguy

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Posted 28 February 2018 - 10:28 AM

And if one wishes to make the data inaccessible without actually fully wiping the drive one can use CCleaner's Drive Wiper tool with a single pass (or anything similar) after doing a quick format.  It writes enough "junk" in random places to make whatever would be reconstructed using a file recovery utility such as TestDisk/PhotoRec be pretty much garbled garbage.


Brian  AKA  Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134 

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#8 Scooterspal

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Posted 28 February 2018 - 11:15 AM

And if one wishes to make the data inaccessible without actually fully wiping the drive one can use CCleaner's Drive Wiper tool with a single pass (or anything similar) after doing a quick format.  It writes enough "junk" in random places to make whatever would be reconstructed using a file recovery utility such as TestDisk/PhotoRec be pretty much garbled garbage.

I like this idea. Since these are off-air TV video files I'd think even messing up a few of the data bits here and there with a tool like this would make the files unplayable, correct?

 

The only catch is these programs take as long as a format do they not?


Edited by Scooterspal, 28 February 2018 - 11:17 AM.


#9 britechguy

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Posted 28 February 2018 - 11:17 AM

It would be my presumption that screwing up a few data bits in each and every block of the free space would render the files unusable.

 

CCleaner allows one, three, seven, and thirty-five overwrite passes.  I can't imagine going beyond three unless what was on the drive was incredibly sensitive in nature.


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#10 Scooterspal

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Posted 28 February 2018 - 11:22 AM

It would be my presumption that screwing up a few data bits in each and every block of the free space would render the files unusable.

 

Question: How does erasing the free space affect the files, then?



#11 Allan

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Posted 28 February 2018 - 11:37 AM

Erasing free space?



#12 britechguy

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Posted 28 February 2018 - 11:42 AM

I am going to try my best to explain "the life of a HDD," simplified.

 

When brand new and unformatted it is entirely blank for all practical intents and purposes.

 

Once you partition it and format the partitions each partition is set up with a file system that allows individual files and folders to be written to it.  It is "effectively blank" until you actually do write files and folders to it.

 

Files/folders are nothing more than a collection of data blocks that form a chain.  Each block points to the next block in the chain until you reach the last block of the file, which then points to nothing.  Every one of those blocks, for a single file, has something in it.

 

For that single file, if you delete it, you do not erase the data, all that happens is that a marker on each block that notes whether the block is free for use gets set to the free state.  All of the blocks contain the data from your file until the individual blocks are grabbed in order to store something else.  This is why undelete utilities can undelete.  They can find a series of blocks marked as free, but where all the blocks of the file are still unused by anything else, and reconstruct the file by grabbing all those blocks and either transferring them to another drive with each marked as "not free" or by marking all of them as "not free".  They only do this when they can find each and every block for a file (and the number of total blocks is stored as part of the data, so if they get part way through and hit a "dead end" because a block was reallocated they just can't recover that file).

 

What you are doing when you overwrite (not erase, though a complete erase/zero-fill is the most thorough way to obliterate what was there) using a drive wiper is just to travel, block by block, on the drive and scramble some number of bits/bytes per block.   When you do that, you are intentionally corrupting whatever was in each block.  Even if a file undelete/recovery utility is used, what it will put back together will have part of the data in each and every block scrambled, resulting in the reconstructed file being unreadable (or at least that's the concept, and the concept works in practice).

 

Drive Wipers generally have the option to wipe only the free space, or the entire drive.   Were you trying to donate a computer or give it to someone else, you generally don't want to wipe the whole drive, just to obliterate "your stuff."  One can do this by setting up a new user account with admin privileges, deleting all other existing accounts, then running a drive wiper on all the free space on the drive.  You don't want to wipe out the OS or the brand new user account and its files, only the stuff that was once used for other user's files that's now marked as free, but still contains the data necessary to undelete files unless you overwrite it.


Edited by britechguy, 28 February 2018 - 11:47 AM.
Added final bit about drive wiper software and how its used

Brian  AKA  Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134 

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#13 Scooterspal

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Posted 28 February 2018 - 11:47 AM

OK. I think I understand. Much appreciated. I'll try using CC Cleaner, then.






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