[tether]

i'm going to transfer my data from my old imac to my new powerbook then sell the imac. before i sell it i want to wipe the drive. how do i go about doing that?

thanks

[SoBayJake]

Once everything is transferred, you can either 1) boot the old computer into target disk mode, connect it via Firewire to the new computer, and use disk utility to wipe it with all zeros (quickier), or multipass wipe of random data (takes FOREVER!)

Or 2) you can boot with the original install disk, open disk utility there, and do the same thing.

-Jake

[TETENAL]

If you used iTMS don't forget to deauthorize.

[tether]

once i'm sorted with transferring my files, i may be back with more questions to check i'm doing it right, but thanks for that.

when i've wiped the drive in that way, would it be possible for the new owner of my computer to still recover/see some of my files?

[SoBayJake]

Originally Posted by tether

once i'm sorted with transferring my files, i may be back with more questions to check i'm doing it right, but thanks for that.

when i've wiped the drive in that way, would it be possible for the new owner of my computer to still recover/see some of my files?

Not much of a chance with zeros, enough that I'm not worried. With the 8-pass random, no.

[chris v]

You could write zeros first, then re-install the default system the machine shipped with using the Software Restore disk. That'd give you a second pass over a fairly large amount of the drive, and it'd be set up all nice for the buyer. Ethically, you should include the original install disks with the machine in the sale, and they could re-install themselves, but it'd be the nice thing to do if they got it with a nice, fresh install. I think if you shut the machine down at the welcome screen without creating a user, then they shoud get the welcome screen again when they start it up.

[ghporter]

I'd go with a couple of passes-one that writes random data and then one that writes zeros. After that, go with the Software Restore disc, so you can demonstrate the machine still works.

If someone REALLY wants to recover YOUR data from your computer, they'd have to use some really sophisticated tools after you just reformated the drive. After one random pass, their odds of success would be miniscule at best, and after more than one pass, PLUS rebuilding the system drive to its factory state, it would be far more costly to mess with than any other method of getting your personal information.

[el chupacabra]

gopher just curious how could anyone get data from the drive if there was even 1 pass of zeroing?

[chabig]

There are special forensic tools that can do this. Ordinary people can't.

[chabig]

Originally Posted by tether

i'm going to transfer my data from my old imac to my new powerbook then sell the imac. before i sell it i want to wipe the drive. how do i go about doing that?

thanks

Before you do anything:

1) Deauthorize the computer in iTunes! Deauthorize both iTunes and Audible.
2) Remove Open Firmware passwords
3) Shut down any Virtual PCs you might be running.
4) Turn the brightness full up and volume nearly so.


To create a clean installation:

1. Install OS X and set it up the way you want it. Install the clean system, create
an admin account, update all applications. You'll see later how to delete
accounts and re-enable setup assistant to run on first boot.

2. Boot from a different volume (e.g. firewire drive, or second volume
on your primary drive). This isn't strictly necessary, but makes
the following easier.

3. Clean up the image (use the GUI or these terminal commands):
rm /Volumes/<imagevol>/var/db/BootCache.playlist
rm /Volumes/<imagevol>/var/db/volinfo.database
rm -r /Volumes/<imagevol>/var/vm/swap*

4. Optional extra cleanup items while the image is mounted:
o To get rid of the admin account you used to set up the machine, use the terminal:
nicl -raw /Volumes/<imagevol>/var/db/netinfo/local.nidb -delete /users/<admin>
rm -r /Volumes/<imagevol>/Users/<admin>
o If you want the restore image to start up in setup assistant:
rm /Volumes/<imagevol>/var/db/.AppleSetupDone

5. Shut down.

[production_coordinator]

I'm a firm believer in installing a new HD when selling a computer.

Why?
- It keeps a nice backup of your old computer (you never know)
- It's the only way to KNOW the drive is empty
- Many people view it as a nice bonus when buying.
- It's cheap ($80 will get you a nice big drive)

I'm a bit of a paranoid, but you never know.

[ghporter]

Originally Posted by el chupacabra

gopher just curious how could anyone get data from the drive if there was even 1 pass of zeroing?

There is a characteristic of magnetic media called "remanance." If you just overwrite with zeros (or ones), sophisticated techniques can detect the overwritten bit values. Some of these techniques have been built into applications that can be run on desktop computers, though most require mounting the physical disk platters on special equipment with supersensitive pickup heads. This is why writing random data is important; it makes such recovery efforts orders of magnitude more difficult. Further, multiple overwrites with different data write patterns (random, FF, 00, random again) makes recovery a virtual impossibility.

A military organization I worked with tangentially used to actually physically disassemble hard drives, segregate the platters, and sand them with an industrial sander to remove the magnetic media completely. While that may sound like overkill, it was 100% guaranteed to ensure the security of any data that may have been on those disks. (I recommended using a wrecking yard crane's electromagnet, but they went to a software solution instead-it would have been cool to see a room full of hard drives hanging from the ceiling for 24 hours, and then watch them all crash to the floor!) Currently, DoD requirements call for multiple passes with mixed write patterns per DoD 5220.22-M. If it's good enough to wipe Top Secret information, it's good enough for me.