I did a backup on the time machine on the old hard drive
[doublepost=1530736947][/doublepost]The unmount option didnt work either.
How I check if there may be some startup script that is referencing something on the HDD?
[doublepost=1530737760][/doublepost]Ok so reset laptop and the erase worked.
Can I check:
What is the rationale for transferring my files back to the old hdd.
Can I just leave them on the desktop of my sdd so it is easier to access my files? Or is it recommended to move back to the hdd? I am referring to the user file which I transferred to my desktop on the sdd before I erased the hdd.
Put the data files which came from the HDD wherever it makes sense for you. If your files all fit comfortably on the SSD, I would just put them there. I have a HDD which is always connected to my computer where I put my downloads, log files from an app server which can get big (gigabytes) pretty quickly when I do certain type of processing and the original install files from various applications, among other files. My media (audio, video) are also stored on HDD's which are also always connected. In the case of my media, there's probably 6TB of it so that obviously can't fit on my 500GB SSD. As for the other files, it's just a matter of avoiding writing to the SSD when I really don't need to. In your case with the Samsung 860 Pro, unless you do something like edit 4K videos all day that then get moved off to a HDD, it's not worth worrying that much about avoiding SSD writes to prolong it's life.