secure deletion question

[KooBrewoP]

Im selling my old power book on eBay soon, and i want to make very sure that all the info is un-retrievable - i had bank stuff, passwords etc. I tried the 8 way random erase, but it keeps on crashing half way through - after about 2 days. So i have just used the write all as 0 setting 5 times then installed the OS, is this good enough?

 

[deni]

Im selling my old power book on eBay soon, and i want to make very sure that all the info is un-retrievable - i had bank stuff, passwords etc. I tried the 8 way random erase, but it keeps on crashing half way through - after about 2 days. So i have just used the write all as 0 setting 5 times then installed the OS, is this good enough?

no, you have to get a hard drive eraser and then erase it with it. and then, you have to start it up again and if it doesnt start or something then it is erased. but to be extra sure, make sure the thing is plugged in all the way cause it might not be and you might just think it is dead when its not but we want it to be not dead when it isn't, or something.

 

[wal9000]

In order to erase your hard drive you're going to need to have a second disk to boot off of. I'll assume that you have your OS X installation disk, which will do the job nicely.

Restart the computer and hold C to boot from the optical drive. It will probably open the installer automatically, but I recall that Disk Utility can be accessed from the menu bar. Open disk utility and select your hard drive in the list to the left.

Next, you need to click on the erase tab in disk util. The options are grayed out for me because I'm booted off of my HD, so some of the instructions below may not be exact. The volume format should probably be set to Mac OS Extended (Journaled). Name is whatever you please, but generally Macintosh HD.

Now click on security options (this is the part I can't check), and you will be presented with a few choices. The first erases everything, but doesn't actually write zeros all over your disk. The second writes zeros everywhere, which takes longer but is more secure. Third option writes over everything 7 (I think) times, which is pretty secure, and the fourth will write over everything 35 times. More writes are more secure, but will take a lot longer. You can just start it going and leave it over night so the time shouldn't really be a problem.

 

[KooBrewoP]

i did the most secure one but like i said it crashed half way through, so i did the one that writes 0 over the HD, i just need to know if someon could get the data from my mac.

 

[djdawson]

i did the most secure one but like i said it crashed half way through, so i did the one that writes 0 over the HD, i just need to know if someon could get the data from my mac.

It would be extremely hard for someone to get any data off your hard drive, so unless the government is after you or someone really wants your data you should be fine.

One of the benefits of using multiple passes is that the drive heads aren't 100% accurate in their positioning, so it's possible for the edges of previous tracks to show through even if you write over it with new data. By running the all zero pass 5 times you've reduced that possibility somewhat. The other way to recover data is to detect residual data from previous tracks, which is what writing random data helps to prevent. You haven't done anything to reduce that other than the fact that you've done 5 passes, which will reduce the amount of residual data from previous data tracks that's detectable.

So, while it might be theoretically possible for someone to extract at least some of your data, it would take a lot of work and require expensive technology that no typical user is going to have (there's no PC software for doing this). As long as you're not an extremely attractive target (e.g. a millionaire or a spy), I'd say you're fine.

HTH

 

[Aniej]

As long as you're not an extremely attractive target (e.g. a millionaire or a spy), I'd say you're fine.

Uhooo, what if I am one of these, what should i do then? haha but seriously, what process are you referring to snd how do you do it when you said:

The other way to recover data is to detect residual data from previous tracks, which is what writing random data helps to prevent. You haven't done anything to reduce that other than the fact that you've done 5 passes, which will reduce the amount of residual data from previous data tracks that's detectable.