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iMac has High Sierra, need help erasing my iMac

Need to reset/erase an older iMac running High Sierra. Need intructiions on how to complete this.


iMac 27″, macOS 10.13

Posted on Sep 24, 2023 12:15 PM

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Question marked as Top-ranking reply

Posted on Oct 5, 2023 9:46 PM

Hi. I just noticed that these instructions (What to do before you sell, give away, trade in, or recycle your Mac - Apple Support) do not include a secure erase (i.e. overwriting every block on the drive.) After an Intel Mac's drive was erased this way, I'd expect that data recovery software can often read the blocks directly and find file content and sometimes even metadata, no? (The formatting doesn't take long enough to write to all blocks.) I'm wanting to prep two Intel macs that can't run the latest OS for sale, each with multiple partitions, and one has a third party hybrid drive; the other an SSD. Erase and reformat a storage device in Disk Utility on Mac - Apple Support clearly says "Secure erase options are available only for some types of storage devices." I'm not seeing the secure erase options. Am I missing something or does following Apple's instructions result in the computer that's handed over still likely to have recoverable user content on it? I'm thinking I need to resort to something like dd if=/dev/random of=/dev/foobar bs=1m in Terminal.




6 replies
Question marked as Top-ranking reply

Oct 5, 2023 9:46 PM in response to Old Toad

Hi. I just noticed that these instructions (What to do before you sell, give away, trade in, or recycle your Mac - Apple Support) do not include a secure erase (i.e. overwriting every block on the drive.) After an Intel Mac's drive was erased this way, I'd expect that data recovery software can often read the blocks directly and find file content and sometimes even metadata, no? (The formatting doesn't take long enough to write to all blocks.) I'm wanting to prep two Intel macs that can't run the latest OS for sale, each with multiple partitions, and one has a third party hybrid drive; the other an SSD. Erase and reformat a storage device in Disk Utility on Mac - Apple Support clearly says "Secure erase options are available only for some types of storage devices." I'm not seeing the secure erase options. Am I missing something or does following Apple's instructions result in the computer that's handed over still likely to have recoverable user content on it? I'm thinking I need to resort to something like dd if=/dev/random of=/dev/foobar bs=1m in Terminal.




Oct 5, 2023 10:56 PM in response to Old Toad

Wow, so I'm right - mostly - there's a risk, but it's smaller than I thought. Per https://www.cleverfiles.com/help/ssd-drive-data-recovery.html, l I need to check if the SSD is old enough that it didn't support TRIM. I remember that in the early days of SSDs, TRIM support was rare.


(Hmm. Post button isn't working. Blacklisted URL? No, login timeout is very short.)

iMac has High Sierra, need help erasing my iMac

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