Why are all my deleted files recovered even after a Secure Erase?

macpokerstars

macrumors member
Original poster
Sep 29, 2010
97
1
I did a seven pass secure erase on my free space on my hard drive (conventional HD, not SSD). using this command:

diskutil secureErase freespace 2 "/Volumes/Macintosh HD"

After it was completed, I used Disk Drill to check whether it could recover deleted files and it did.
It looks like secure erase is not working.

How can I securely erase free space on my hard drive?
 

treekram

macrumors 68000
Nov 9, 2015
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405
Honolulu HI
Did you empty the trash before doing the secureErase? The other possibility is if you have a laptop with Time Machine as I believe there is a file that can get created with a backup of some of your files (I can't remember the exact details). Also, some programs will make copies of files. For example, by experience I know that TextEdit makes a copy of the file you're editing but haven't saved every so often in case of an unexpected shutdown (in my case, there was a power outage and when I turned the machine back on, TextEdit re-opened the file which I did not save).
 
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macpokerstars

macrumors member
Original poster
Sep 29, 2010
97
1
Hi there,
Thanks for your response. I have never used Time Machine.
My computer spent 5-6 hours secure erasing free space on my 1TB hard drive, but Disk Drill finds all deleted files effortlessly and they are intact.
Please let me know if you have any suggestion.
Thanks
 

BeefCake 15

macrumors 65816
May 15, 2015
1,465
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near Boston, MA
Hi there,
Thanks for your response. I have never used Time Machine.
My computer spent 5-6 hours secure erasing free space on my 1TB hard drive, but Disk Drill finds all deleted files effortlessly and they are intact.
Please let me know if you have any suggestion.
Thanks
Have you tried it through a third party software? CCleaner or others?
 

Yahooligan

macrumors 6502a
Aug 7, 2011
965
113
Illinois
Looks like you skipped over the other question that was asked; Did you empty the Trash before running the secure erase?
 

KALLT

macrumors 603
Sep 23, 2008
5,136
3,184
Apple discourages the use of this command due to its limitations. You should not use it. Either you encrypt the disk or erase it completely.

Moreover, a 7-pass overwrite is considered unnecessary, a single-pass, zero-fill erase is generally sufficient.
 

macpokerstars

macrumors member
Original poster
Sep 29, 2010
97
1
Have you tried it through a third party software? CCleaner or others?
I tried CCleaner and unfortunately, it changed nothing. Even after I did a 7-pass THEN a zero-out of the free space, Disk Drill still found every single file that was there before. I erased previous Disk Drill sessions, but it still found all files again.

Looks like you skipped over the other question that was asked; Did you empty the Trash before running the secure erase?
Yes I did but it didn't help, unfortunately.
 

BeefCake 15

macrumors 65816
May 15, 2015
1,465
1,903
near Boston, MA
I tried CCleaner and unfortunately, it changed nothing. Even after I did a 7-pass THEN a zero-out of the free space, Disk Drill still found every single file that was there before. I erased previous Disk Drill sessions, but it still found all files again.
Did it find the file still functional or just metadata?
 

treekram

macrumors 68000
Nov 9, 2015
1,849
405
Honolulu HI
I would suggest the following: Buy an external 1TB HDD. Clone your internal HDD to the external. If you don't already have cloning software, you can get CCC free on a trial basis. (CCC is good for this purpose because the current version will copy files, not sectors - for what you want to do, you don't want software that will copy sectors). Format and erase the internal HDD using a 2-pass or whatever. See if Disk Drill can find the files. It should not be able to find the files on the internal HDD. Then see if it can find the files on the clone. If it can find the file on the clones, then you didn't delete some file that contains your data. If it can't find the files, then you have a method that will work for secure erasing.

Let us know how it turns out.
 
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