[SoftTalker]

All you really need to do is write one pass of zeros on them. That will prevent anyone but a very dedicated adversary with expensive equipment from recovering any data, especially on TB scale drives.

Can still take hours per drive though, which is why a lot of people skip it.

[krior]

Or encrypt it and just trash the encryption header.

[edoceo]

I make a random 1MB chunk, then write that all over the drive, at overlapping offsets. I've been told that really clears it. On IDE-spinning-rust disks I trusted it, not sure if I should trust these modern SSD

[p1mrx]

Why rewrite the same 1MB chunk, instead of making new random chunks?

Redundant data at least opens the possibility that the drive could deduplicate.

[edoceo]

Cause making new random was taking too much time.

[throwawaymobule]

Pretty sure most modern computers can generate random data faster than they can write to a disc.