Started migrating my old 5 rig a while ago. Had a couple of probs with connectors and the usual stuff, but got it up and running. Except for one drive. It is currently disabled, and the only thing I can see is 4 CRC errors in SMART. Luckily I saved the syslog from that first boot when the drive went AWOL, and a bit later a full diagnostics file. I'll attache the syslog here and add the diags file in a moment. In this syslog things start to derail at 12:31:10. 

Obviously unR want nothing to do with the drive right now, but can I make it change it's mind? Could there have been a dusty connector or other fixable problem causing this? Oh, the array is up and running, but degraded.

syslog.zip

Here's the diags files, for anyone interested.

tower-diagnostics-20180603-1303.zip

Disk looks fine, you should replace the SATA cable and then can do a rebuild:

http://lime-technology.com/wiki/Troubleshooting#Re-enable_the_drive

Thanks JB. Since this is a process involving moving all drives to a new chassie and everything around it, I'll just try cleaning and reseating everything, then make a rebuild. That ought to show if it was just a stroke of bad luck, or bad HW.