Apple hard drive
March 2, 2005 4:23 PM   Subscribe

I have an old iMac that I want to get rid of and I want to erase the hard drive before I give it to someone/recycle it. The computer is screwed up (battery died, long story), and the only way I can erase it is to go up to the "erase" option in the drop down menu. I did that, and it seemed to work. Then, I reinitialized the hard drive. Does this mean it's really erased completely, or is the info still on there?
posted by braun_richard to Technology (17 answers total)
Initialization does nothing beyond deleting the "index" pointing to files. All the files still exist on the hard disk. When you delete a file in the trash or recycle bin, it merely removes the pointer. Over time, bits and pieces of other files might write over bits and pieces of the original making it less recoverable.

In order to make files less recoverable on purpose, the drive needs to be zeroed (Apple tech doc). Each zero makes the drive less recoverable...there is a reside left over by magnetic drives. Your best bet is to follow the directions in the tech doc.

Be forewarned: a rough estimate is for every 20 gigs, it takes an hour to zero, give or take.
posted by pedantic at 4:43 PM on March 2, 2005

If you don't want to zero it, take the HD out & drill through it. Or smash it. Someone wanting to bring the machine back to life would probably want to have a larger HD in there anyway, and that is not expensive.

As pedantic said, the data is likely still recoverable unless you zero it or do something similar used a more specialized tool such as Norton or Tech Tool Pro.
posted by omnidrew at 4:47 PM on March 2, 2005

yeah, what these guys said. If you're super concened, do the zeroing process three times.

Once whould be good enough for to prevent anyone but a seriously dedicated snoop form retrieving your erased files.
posted by pmbuko at 4:55 PM on March 2, 2005

If it takes less than a minute, no, it didn't permanently erase the drive. Zeroing the drive can take an hour or more.
posted by kindall at 5:08 PM on March 2, 2005

Response by poster: Actually, that Apple doc is for OS X. I have an old iMac with OS 8.6.

Erasing the hard drive (using the drop down menu option) and then initializing it doesn't erase the data? Huh. I'll have to figure something out. Thanks for the info.

Related question: what's the best way to dispose of (not give it away or recycle it) a computer? I know that local dumps, etc frown upon people just throwing out their computers because of environmental concerns.
posted by braun_richard at 5:12 PM on March 2, 2005

Hmm, shouldn't you actualy write random data to the drive before zeroing it?
posted by delmoi at 5:48 PM on March 2, 2005

for os 8.6 there was an option in disk utility to do something like Zero three times.

Or was that in OS9?
posted by filmgeek at 5:51 PM on March 2, 2005

braun: contact your local city recycling. They should be able to point you in the right direction. Also, OS 8.6 and 9 have the Disk Utility as well. I remember zeroing a number of times (back when I thought it would somehow help a bad drive).

delmoi: A little research posted this nugget: Department of Defense destruction criteria on each storage media type. In short, they recommend three passes.

First pass: 0
Second pass: 1
Third pass: random 0 or 1 for every bit
posted by pedantic at 6:12 PM on March 2, 2005

Darik's Boot & Nuke: "it's a self-contained bootable floppy/CD that securely completely wipes the hard disks of most computers. There's even a Mac version now." I can't vouch for it, just relaying what I read.

Via (That link goes to a very interesting article about unwiped drives, btw.)

Have you tried checking mac-specific forums? Like or
posted by Jim Jones at 6:18 PM on March 2, 2005

Response by poster: The computer is completely screwed up, and not connected to the web, so I can't download anything.

I can't even FIND the Disk Utilities! I erased the hard drive then reinitialized it, and half the stuff I try to do I can't find anymore. How would I access the disk utilities?

I just want to make sure I don't have any personal info on the computer, that's why I'm a little antsy about giving it away to someone or something similar. I'd rather completely wipe the hard drive and/or throw it away some place.
posted by braun_richard at 6:27 PM on March 2, 2005

If you don't have the original 8.6 CD-ROM or even an OS X CD-ROM from another computer or friend (Disk Utilities is on both), then physically taking the drive out and having some fun with it might be easiest.

You could also try burning Darik's PPC version to a CD and booting from it by holding down C. Never used it, so I'm not sure if it just that easy.
posted by pedantic at 6:43 PM on March 2, 2005

Response by poster: I'm very open to physically taking out the hard drive and destroying it, but two questions: is it safe to do (not sure what's in there, lead and whatnot), and if it is safe, how do I even figure out where it is/what it looks like, etc?

Thanks for all your help, btw.
posted by braun_richard at 7:21 PM on March 2, 2005

Short on time? Put a big speaker magnet on top of the drive. As Keiser Sose says, "Ffft."
posted by squirrel at 7:26 PM on March 2, 2005

The author of Applied Cryptography recommends 7 passes! First all zeroes, then all ones, then 5 passes of random 0s and 1s. Even then, he doesn't make any promises other than that a sufficiently motivated person or organization (read: NSA) could probably still recover the data.
posted by knave at 9:12 PM on March 2, 2005

how do I even figure out where it is/what it looks like, etc?

Guides below, cracking the case varies a bit depending on the type of CD-ROM drive the machine came with:

Hard disk removal for a tray loading iMac.

Hard disk removal for a slot loading iMac.
posted by jalexei at 7:44 AM on March 3, 2005

Response by poster: jalexei: Thanks for the links to the slot loading iMac info. That helps a lot.

So opening up an iMac (and any computer) is safe for a layman to do? I'm thinking about anything inside that might cause injury or you wouldn't want to be exposed to.
posted by braun_richard at 11:52 AM on March 3, 2005

So opening up an iMac (and any computer) is safe for a layman to do?

Generally yes. The iMac is a bit trickier than an average tower computer because stuff is packed in there pretty tightly, but if you're reasonably comfortable with taking things apart and you can follow the directions you'll be fine.

In short: Read and understand all of the instructions before you begin; have a clean, open space in which to work; gather any needed tools or materials beforehand and have them in easy reach. Most importantly, be patient and take your time.
posted by jalexei at 12:04 PM on March 3, 2005

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