I'm trying to erase an external disk drive that I had been using as a backup disk. There are no options for me to securely erase – the option just isn't there at all.
It is currently formatted as MAC OS Extended (Journaled, Encrypted).
I have a second HDD drive that when mounted shows the security options when erasing.
Any ideas what is going on here? This is a new problem for me; I'm sure I've secure erased this disk before.
Edit: I've just noticed that the only difference between the two disks is that the one that could be securely erased is down as a 'USB External Physical Volume' whereas the disk I'm having the problems with comes up as a 'CoreStorage logical volume'. Is this the issue?
Best Answer
MacOS doesn't let you do a Secure Erase on encrypted volumes because there's no point: a single erase will delete the encryption keys; and any residual data on the disk will be meaningless junk that cannot be decrypted.
Multiple zeroing of a mechanical disk can put significant stress on it and shorten its lifespan.
Similarly, MacOS doesn't let you secure erase SSDs, because that's also a pointless exercise: doing the erase doesn't actually make it more securely erased.
Why is a secure erase 'not necessary' for SSD's?