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Erase ext. hard drive securely before sale - recommendations?

Dowjohnny

Dowjohnny

macrumors 6502a
Original poster
Jul 5, 2011
506
246
Germany
Hi everybody

i'm looking to sell two of my older trekstor external hard drives (no SSD). Of course i do not want the buyer to be able to recover my data (even after formatting the drives before sale). There has been no real "sensitive" information on them but it just would give me a better feeling.

Can anyone recommend a good way to do so? Especially any software tools for mac? I've looked through some google results but found mostly windows based software with very bad reviews etc.. What i've learned is to use a eraser program that overwrites the drives several times instead of just deleting them..

Any help is appreciated =)

regards
Dowjohnny
 
Dowjohnny

Dowjohnny

macrumors 6502a
Original poster
Jul 5, 2011
506
246
Germany
Wow thanks, it didn't come to my mind to check the built in options on my mac :D As always Apple has thought about everything ;)

Thank you! I think i'll go with the 7pass since it is not an SSD so no increased wear to the drive!
 
maflynn

maflynn

macrumors Haswell
May 3, 2009
73,486
43,410
Agree with the other poster, just go with what apple provided, i.e., Disk Utility :)

The 7 pass erase will take a long time so be prepared to let the puppy run for a while.
 
J

jeremysteele

Cancelled
Jul 13, 2011
485
394
Mr. Retrofire said:
Is this really necessary? One pass (zeroes) is not enough!?
Click to expand...

One is enough. Studies have been shown that one pass (full zeroes) makes essentially impossible (unless you have access to better equipment than an electron-microscope) for anyone to read any actual chunks of data off a magnetic drive (or in the case of an SSD, they include builtin functions for clearing of data).

Write heads on modern drives are accurate enough that they don't leave anything behind (an issue with previous drives, which (incorrectly) inspired 35-round wipes to be implemented in the 90s and early 00s).

Although some people are paranoid, so if you want to cause a ton of premature wear (and yes, with magnetic drives - writing over and over causes a TON of wear, mostly due to the heat generated) on your drive - go right ahead with a 7 or 35-round wipe.
 
Last edited:
Dowjohnny

Dowjohnny

macrumors 6502a
Original poster
Jul 5, 2011
506
246
Germany
Well thanks for that education, i thought the wear was only an issue of SSDs but in this case maybe a single run is really enough. Especially since there is no important data on the drive!

Thanks for all your help
 
maflynn

maflynn

macrumors Haswell
May 3, 2009
73,486
43,410
Dowjohnny said:
Well thanks for that education, i thought the wear was only an issue of SSDs but in this case maybe a single run is really enough. Especially since there is no important data on the drive!

Thanks for all your help
Click to expand...

I think a seven pass zeroing will cause negligible wear and tear on your hard drive. I do think its over kill but I don't think you'll prematurely wear out the hard drive because of that. SSDs is different, you definitely don't want to do a 7 pass on those
 
B

barkmonster

macrumors 68020
Dec 3, 2001
2,134
15
Lancashire
A single pass zero will also expose any damage to the drive you may not even be aware of so I'd do it before selling just make sure it still actually functions. I have various drives from older Macs I keep around for backup and the drives that survived a zero formatting are still usable even now. The odd thing was, a 6Gb ATA drive from a 17 year old Mac works perfectly, a 40Gb ATA drive from a 12 year old Mac was a dud after zeroing.
 
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