@OpenSourceUser Was this after a kernel update, ie can you try booting from a previous kernel version to see if it’s a compatibility issue with a newer (and default) kernel.
From a quick look at libata_error_messages it would appear to suggest a hardware issue. So re-seating all connectors and testing hardware using live boot systems to try and diagnose further ie running smart tests using live linux distro’s or just seeing if all the drives show up, and looking at the dmesg of those live boots.
After several reboots (and I mean a lot of reboots) the system was running again… but only once. So I rebooted the system again and again until I was able to install the latest testing update (3-8-12.04). Seems like the problem is gone with kernel 4.4.5-1
I’ll keep you updated