Aloyloy

Thank you very much for the assistance and the link (https://docs.unraid.net/unraid-os/manual/storage-management/#rebuilding-a-drive-onto-itself)
 
I learned something about unraid which is good, how to properly rebuild. But because I did not understand that I'm not sure which of the MANY things I did resolve the issue (change power cables, change SAS to SATA cable, etc). However it now appears to be resolved. It rebuilt without issue and even completed its weekly parity check with no problems.

I apologize for wasting everyone's time. I am a moron when it comes to Linux and the solution was so dumb. It was all due to the lack of a proper GUI.

In midnight commander I was selecting the files I wanted to copy then selecting where I wanted them to go on the right. Then hitting the copy button. Thus I was sending the files the WRONG DIRECTION. So it was the old 8tb that was full, not the 16tb I was copy to.

The answer was. I had two drives fail. One was the Parity drive.

Well the GOOD news is I fixed the mover issue. It was indeed the setting I was using. I had it on preferred because apparently I don't comprehend directions the first few times. Once I put it to just "Yes" on use Cache pool and started the mover again the available space on the cache is slowly climbing. So yay to that.

Now I just gotta figure out those errors in the diagnostics and someday maybe why my cache isn't performing how it did at the start.