System hanging when trying to spin-up from HD idle

[cmrho]

So there is no wakeup with STOP@135W.
I guess values 2 and 3 are what you've set up with sdparm anyway itself...

https://manpages.ubuntu.com/manpages/xenial/man8/sg_start.8.html
sg_start --start /dev/sdX vs sg_start --stop /dev/sdX

I think a SCSI/SAS STOP mode is a special mode and only meant for maintenance*.

Edit:
*https://www.t10.org/ftp/t10/document.08/08-126r0.pdf
page3

I'm going to call off any further work on this. I've never had so much difficulty putting drives into standby, lol. SATA disks are way easier. I got a fantastic deal on these relatively new drives, but I might be paying for it in the long run (in electricity). Thanks again for all of your assistance!