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How to securely erase a Mac OS X hard drive

S

sethypoo

macrumors 68000
Original poster
Oct 8, 2003
1,583
5
Sacramento, CA, USA
I am going to be selling my trusty 12" PowerBook G4 to a friend soon, and putting the money I get from that towards a last revision 15" PowerBook G4. After I transfer my data from the 12" to the 15", I want to completely and securely erase my hard drive. The thing is, I don't know how to do this! I've never formatted/erased a hard drive before.

So, how do I do it?

Thank you!
 
Take the install disks and do a fresh install of the OS. Just don't select "Archive and install" or else you'll be saving all your old information too.
 
Applications > Utilities > Disk Utility

Pick your drive and hit Erase. Then pick the Security option. Pick your level of formatting paranoia.
 
Ok, so you two have given me two different ways to erase my hard disk. Which one is more secure? Not that I have anything to hide, I just don't like the idea of someone going through my data without my permission.
 
sethypoo said:
Ok, so you two have given me two different ways to erase my hard disk. Which one is more secure? Not that I have anything to hide, I just don't like the idea of someone going through my data without my permission.
Click to expand...
Just pop in the OS X DVD then. Hold 'C' when the Mac boots and it'll boot off of the DVD. When you try to install OS X it'll give you a warning that it can't install onto the hard drive. It'll have you pick between "Archive and install" and "Erase and install". If you have nothing to hide just "Erase and install".
 
1. Insert the Mac OS X Install disc that came with your computer, then restart the computer while holding the C key.

2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.) Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.

3. Select erase and then Security Options.

4. Select the level you desire (zero data, 7 pass or 35 pass) then erase.
 
You can format and zero out the drive ... and reinstall the OS.

Note: It will take awhile, especially multi pass.

I would fill up the drive with the Barney's Greatest Hits by duplicating over and over, and then tossing. Should give them something fun to recover as they listen to Barney endlessly.
 
Eidorian said:
Just pop in the OS X DVD then. Hold 'C' when the Mac boots and it'll boot off of the DVD. When you try to install OS X it'll give you a warning that it can't install onto the hard drive. It'll have you pick between "Archive and install" and "Erase and install". If you have nothing to hide just "Erase and install".
Click to expand...

You're a little vague, so I will take your post to mean that installing from the CD is not as secure.
 
DZ/015 said:
1. Insert the Mac OS X Install disc that came with your computer, then restart the computer while holding the C key.

2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.) Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.

3. Select erase and then Security Options.

4. Select the level you desire (zero data, 7 pass or 35 pass) then erase.
Click to expand...

This sounds like my best option. Thank you!
 
DZ/015's method is the best option in terms of security. I do think the 35-pass erase is overkill, and it'll take forever. Single pass is quite possibly good enough. If you're worried about that, 7-pass is still reasonable in terms of time.
 
iMac erasing

OK...I have an old old old iMac that I got from an old old job of mine...I've recently gotten a new ibook and want to get rid of the hulking piece o' crap that is the imac...

how do I erase it though (there might be some old info from my previous job on it)? it's running OS 9.2...if that matters

when I put in either CD that came with the new mac (OS 9 Install or OS X Install) and hold down the c key (assuming we're talking about the letter 'C' and it's not some weird key abbreviation) it simply spits the damn CD out...

in fact, no matter what I do, it spits the CD out...

also, there is no Disk Utility option anywhere in the stupid computer :(

help!
 
emw said:
Here's a shareware app that should do it. I have to admit, I'm not real familiar with OS 9 stuff anymore...

http://www.versiontracker.com/dyn/moreinfo/macos/3994
Click to expand...
Is simular to Burn are simular. They create a file that contanes artifical data and then let the OS save it.

There really isn't reason to use OS 9 to erase free space.

This is one of the tried, true and simple ways of erasing a HD. It's isn't any diffrent that OS X's method, which is the same. The old school way of deleting an HD, if you couldn't write a utility that created an artificial file, was to cut and paste together or stitch together a number of text files (or any other) and save them to the disk again and again. (As SunBaked sans Avatar notes) OS X's method is quite secure, and even if all you do is erase the free space, you will be fine.

You needn't do multiple passes, unless you expect people to remove the jewel from the HD and place it in SEM attached to special imagine software, and then have it virtualy rebuilt by some sort of super computer. Basically, if your afraid of the Men in Black, then by all means do a 35 pass overwrite and then deGauss the whole drive. Then again, deGaussing a drive generaly renders it usless.;)

A side note: Another way to erase a HD with out writing a an adressable file is to directly address sectors of a drive and write information to them, but this takes more time. The method of writing a file containing all zeros (not just ASCii 0's but, because that really isn't a zero) is secure enough. It also saves on code.
 
Erase problem

My friend wanted to securely erase her hard drive before donating it to a group. She began the process from the Leopard install disk which has the option for 7 passes. She said that after 3 passes she saw a message to restart the computer so she did. Now she can't install the OS or anything. Any suggestions?
 
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