shred --verbose --random-source=/dev/urandom --iterations 10 --zero /dev/sda
So, the total data destruction is in progress, and I have no question about it.
The reason I am asking you about instructing me how to do the Secure Erase came to me from another SE site, more specifically this answer, which led me to thinking, there may be one final round of this pre-sale preparation. I came across some host protected area, which I am unsure, whether my command erased even that or not.
I am unsure whether just go ahead and do things mentioned on this web page, or only wait for the aforementioned command to finish and sell it right away.