7 Pass Secure Erase - good enough to return hard drive?

netnothing

macrumors 68040
Original poster
Mar 13, 2007
3,674
305
NH
So I may have one of the Seagate hard drives that are failing badly. Haven't heard back from Seagate to see if my drive and firmware is bad, but since I just bought the drive, I'm thinking of returning it.

I'm in the middle of a 7 Pass Secure erase on it (1TB).

Do people feel comfortable returning a drive after doing that erase? Or should I just forget about it and destroy the drive and chalk it up to a loss?

-Kevin
 

Jack Flash

macrumors 65816
May 8, 2007
1,160
7
You have to ask yourself... what data are you so worried about being uncovered?

7 passes of zero's is the DOD standard. You're fine with that.
 

emt1

macrumors 65816
Jan 30, 2008
1,384
20
Wisconsin
One pass would've been enough. To recover data after a one-pass wipe the person would have to perform the data recovery in a clean room and would have to physically dismantle the hard drive.
 

dvdhsu

macrumors 6502a
Mar 28, 2008
964
0
Palo Alto, CA
7 Pass is definitely enough. The only reason I would 7-pass it would be if I had illegal things on my HD, and I was knew that somebody was trying to get my information.
It that is your case, then by all means go ahead and zero it out.
Otherwise, it is good to go.:)
 

Jethryn Freyman

macrumors 68020
Aug 9, 2007
2,329
2
Australia
Data can be recovered if the disk has been "zeroed", this is done by examination with special electromagnetic equipment to determine what the previous binary state of the magnetic tracks were. So a really determined person could get at your data - but I don't see the guy at your local electronics store splashing hundreds (thousands?) of dollars on the equipment.

Of course, you may as well do the 7 pass erase just for fun. I really need to keep my data secure, and it's what i do.
 

Matek

macrumors 6502a
Jun 6, 2007
535
1
Well, what kind of security issues are we talking about here? If you own a company that deals with touchy information and you're afraid your competition might get the drive from your hardware supplier, which could hurt you a great deal (financially), destroy the drive yourself. But I'm pretty sure you would be aware of that fact if you were in the described position.

If you simply want to make sure someone doesn't get a hold of your online banking certificate and some raunchy pictures of your girlfriend, a 7 pass secure erase is more than enough. There is no absolutely no way a prankster at the local computer shop can find anything with data recovery software on your drive after this procedure and as other people mentioned - the odds of him paying loads of money for professional data recovery are extremely low.
 

2ndPath

macrumors 6502
Feb 21, 2006
355
0
I just read about an article related to this topic. I didn't read the article myself, but only about it:

The article:
http://www.springerlink.com/content/408263ql11460147/
The article about it (only in German):
http://www.heise.de/newsticker/Sicheres-Loeschen-Einmal-ueberschreiben-genuegt--/meldung/121855

Apparently they tried to reconstruct data after a one pass overwrite using some very low level methods (magnetic mircoscope). Their conclusion is that for practical purposes it is not possible to reconstruct complex data.

Also the wikipedia article on data recovery states that the possibility to reconstruct overwritten data has been suggested in 1996, however, even until today no one proved to be able to do so.

http://en.wikipedia.org/wiki/Data_recovery

If this information is right, you should be perfectly fine with your 7 pass overwrite.
 

netnothing

macrumors 68040
Original poster
Mar 13, 2007
3,674
305
NH
Thanks for the replies everyone.

No, nothing illegal on the drive. :p

It was being used as a secondary backup to my Time Machine drive. So I had manually copied over everything in my home folder (all Mail, documents, etc), as well as a backup of the drive that holds all client work (this is my business computer).

@mcavjame - it's a 1TB drive, and Disk Utility has estimated 16 hours. I still have 4 hours to go.

Basically, I just don't want either the Best Buy Geek Squad trying to look at the drive because they are bored on their lunch break :p or that they sell the drive again as a return and some geek gets it knowing that it's been returned and wants to poke around.

Thanks everyone for the info.

-Kevin
 

Riemann Zeta

macrumors 6502a
Feb 12, 2008
661
0
Data can be recovered if the disk has been "zeroed", this is done by examination with special electromagnetic equipment to determine what the previous binary state of the magnetic tracks were.
As people have mentioned above, this idea of "ghost electromagnetic signatures" forever remaining on a disk is more of an urban myth than actual science. Even if this phenomenon were physically valid--and no one has yet been able to demonstrate that it is--modern HDDs are so high-density that it would take millions of dollars worth of bleeding-edge magnetic resonance force microscopy equipment to even attempt to undertake such a procedure.

So unless you work for the NSA and just happen to have the schematics for the nuclear football on your drive, I'd say 7-pass erase is secure enough.

Edit: Wow, according to that 2008 Notes in Computer Science paper posted above--a real interesting read--the probability of recovering a single continuous KB (1024byte) of data post-wipe from a used circa-1990 drive by magnetic resonance force microscopy is around 1.400E-258. Damn!
 

Jethryn Freyman

macrumors 68020
Aug 9, 2007
2,329
2
Australia
As people have mentioned above, this idea of "ghost electromagnetic signatures" forever remaining on a disk is more of an urban myth than actual science. Even if this phenomenon were physically valid--and no one has yet been able to demonstrate that it is--modern HDDs are so high-density that it would take millions of dollars worth of bleeding-edge magnetic resonance force microscopy equipment to even attempt to undertake such a procedure.

So unless you work for the NSA and just happen to have the schematics for the nuclear football on your drive, I'd say 7-pass erase is secure enough.

Edit: Wow, according to that 2008 Notes in Computer Science paper posted above--a real interesting read--the probability of recovering a single continuous KB (1024byte) of data post-wipe from a used circa-1990 drive by magnetic resonance force microscopy is around 1.400E-258. Damn!
Thanks - morale of the story here is than zeroing out the disk is enough.
 

Amdahl

macrumors 65816
Jul 28, 2004
1,438
1
Why don't you wait for Seagate to respond? I have 3 of the drives on the possibly buggy list. But unless the drive has failed, there is no problem at this time. Once it has the firmware update, the problem is solved. If the drive controller fails before then, Seagate will fix it. The data is not lost.

But, if you don't have access to Windows or don't want to deal with the firmware update, then returning may be best for you.
 

netnothing

macrumors 68040
Original poster
Mar 13, 2007
3,674
305
NH
Why don't you wait for Seagate to respond? I have 3 of the drives on the possibly buggy list. But unless the drive has failed, there is no problem at this time. Once it has the firmware update, the problem is solved. If the drive controller fails before then, Seagate will fix it. The data is not lost.

But, if you don't have access to Windows or don't want to deal with the firmware update, then returning may be best for you.
That's what I'm doing for right now. Here's hoping that they actually resolve the issue with new firmware.

I have a feeling Seagate is losing a fair amount of customers with this. I know I'm going for a different brand the next time I need a new drive.

-Kevin
 

Amdahl

macrumors 65816
Jul 28, 2004
1,438
1
I have settled on Seagate as my preferred brand after having plenty of Maxtor deaths, hearing about the IBM deathstar incident, having a sudden death IBM SCSI drive, and a lot of dead WD Caviar in the late 90s. But I have never had a Seagate die on me (yet). Now that I use Seagate almost exclusively, I guess it is only a matter of time.

Of course, times change, and perhaps Seagate is slipping. But considering this current incident is a firmware problem on the controller, and not a data integrity problem, I'm not going to take it in to consideration, as long as Seagate addresses it properly.

On the third hand, this is the 2nd significant firmware problem with this drive series. The first problem was that the early firmware on some of the drives would only use half the cache memory on the drive.
 

geerlingguy

macrumors 6502a
Feb 11, 2003
562
6
St. Louis, USA
Unless you have top-secret CIA information on the drive, and someone would be willing to invest some serious time and $$ into getting the data from your drive, one pass would be fine.
 
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