Post says it all basically. Started having what appeared to be major drive/io usage off and on around a month ago. System would become unresponsive sometimes. Even had to force several restarts. Have been trying to troubleshoot off and on. Appears to be IO wait as it happens with certain dockers running, downloads being moved from cache to array, and during parity checks. But problem came out of nowhere. Last night same thing. Plex stopped responding and then everything went with it including the web ui. I let it sit overnight and it was still working away with the constant HD led blinking on the case. So I forced it down and it would not come back as it doesn't see the flash drive as a viable bootable source. Tried making another from a Connect backup and no dice still wont see it as bootable. Tried a new USB stick and different ports...same. 

I'm at my witts end as to where to go from here. So much work and configurations possibly lost. Not to mention a frustrated wife who I have got hooked on Mealie, Plex, and Home Assistant. Not sure how to get the flash backup to boot. And if I can't and have to start fresh I have some items backed up on the array but man so many configs with the Reverse Proxy alone.

Any thoughts or help much appreciated. Maybe if only to commiserate. Also this IO wait stuff due to FUSE is a tad ridiculous for a OS that is supposed to be able to run on anything and stably. 

Is it possible to install a fresh one and then point it to where the appdata is on the ssd cache drive and have it all re-populate with all my configs?

Alright after delving deep and many many usb sticks and BIOS settings I figured it out. But man guys this should really be easier and included in the Unraid Installer. I had to install with Rufus a bootable Debian ISO to the usb stick, with the fix old Bioses feature enabled. Then delete everything on it manually. Then copy over my backed up flash drive contents, and make sure to not hit the make bootable or change the EFI- to EFI. Then and only then I could get a Unraid stick, new, old, or restored, to work. Eesh.