I have a bunch of old 3 and 4TB hard drives that I am going to get rid of, and I want to securely wipe them. I started securely wiping a 4TB drive late Thursday with the most secure settings and it is still going through the process as of right now on Monday morning.
1. Are the most secure wipe settings overkill for hard drives? What would it take for someone to recover my data using a lower secure wipe setting?
2. Is the process/speed of wiping the drive dependent on the speed of my Mac in any way?
3. What is the equivalent of securely wiping a SSD?
Going forward, the best option is to always encrypt the drives, then when it comes time to dispose, you can just format them (destroying the boot sector info aka cryptoshredding) without wiping. Still recommend drilling them to be safe.
For unencrypted disks or SSD's, I format them then go to terminal, cd to /volumes/diskname and run dd if=/dev/zero of=./wipefile.txt bs=65536
That fills the entire disk with 0's. For 99% of the people, it's more than enough (unless you're a target of a nation state, multi-pass wiping is almost always overkill). Then I drill the disk and dispose.
If an unencrypted drive has actually failed, I open the drive itself up, extract the platters, drill them, and then bend with two pairs of pliers.
One note on SSD's - because of garbage collection, it's always good to encrypt them - that way if sectors are removed from access, there's no unencrypted data on them. That's one reason I drill each individual chip on SSD's when disposing.
And on encrypting - it's important to do before
putting any data on it. Depending on how it's done, FileVault will not always encrypt unused space, so if you've deleted files or formatted the disk, you're likely to have leakage.