I have an external drive enclosure with two 2TB drives in a JBOD configuration. When I was trying to read files from the drive, many of them were throwing up error -36.

The problem is, I don't know which disk of the two (or maybe both) are bad. If one of them is still good, I'd like to keep it and continue using it.

After searching around on Google, I didn't find anything helpful. So, I took one drive, put it in a new, single-drive enclosure. I ran:

diskutil secureErase 0

on the drive, and it seemed to complete the operation fine. But, does that mean there were no errors? I don't know what diskutil would do if there were problems with the drive.

I've started the other drive going, but I thought during the 18 hours it takes, I would ask here to see if anyone had any better ideas.

EDIT

smartmontools is what I was looking for. It seems that DriveDX as mentioned by /u/gobbo is almost just a GUI frontend to the CLI tools.