What to do before selling or giving away your Mac

Discussion of general issues, not related to a specific Mac or iDevice operating system.
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Stephen Hart
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What to do before selling or giving away your Mac

Post by Stephen Hart » Fri Jun 28, 2013 9:53 am

What to do before selling or giving away your Mac

Note especially that you must sign out of iCloud before deleting any data.
Also, Disk Utility's erase feature can write zeros across the whole drive (takes hours) or do that repeatedly (takes many hours).
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Stephen Hart
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Re: What to do before selling or giving away your Mac

Post by Stephen Hart » Tue Jul 09, 2013 7:31 am

The Apple knowledgebase article posted on Macintouch engendered a long (some would say long-winded) discussion of hard drive erasure and security.

As I've said in the past, the bottom line is that if you want absolute certainty, replace the drive in the Mac and destroy the old drive.

But if you're not a spy, and you just want to prevent a new owner from finding your bank account information, using Disk Utility to overwrite the drive with zeros is plenty good enough.

Here's what Disk Utility Help has to say:
Writing over the data three times meets the U.S. Department of Energy standard for securely erasing magnetic media. Writing over the data seven times meets the U.S. Department of Defense 5220-22-M standard.
Note that Disk Utility help also says:
You can’t securely erase a CD, DVD, or a solid-state drive. If you don’t want data recovered from a solid-state drive, use full disk encryption.
(emphasis added)
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Re: What to do before selling or giving away your Mac

Post by Stephen Hart » Sat Aug 31, 2013 1:22 pm

I just did this procedure with a PowerBook G4 that I gave away. And I made a mistake that I'll document for the benefit of SMUG.

I had the PowerBook running in Target mode so that I could erase and zero the drive.
The mistake I made was setting up the new partition as GUID, the partition format used on all current Macs. What I should have done was to use Apple Partition Map, which is the format needed for older OS versions, like 10.5, the latest this PowerBook can use.

This is easily fixed during installation with the OS DVD. It will show an error message saying it cannot install Leopard on this drive. But it goes on to detail the fix:
1. Start Disk Utility from the Utility menu.
2. Set up the drive with a new partition using APM.
3. Quit Disk Utility and continue with the installation.

AppleCare techs, by the way, missed this entirely, and mistakenly told the new owner that he needed Tiger, not Leopard.
"Design is not just what it looks like and feels like. Design is how it works."
Steve Jobs

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