The other day a disk red-xed.  I didn't know to get the syslogs before restarting but based on SMART after restarting johnnie.black suggested it was a SATA cable error.  I replaced the cable and rebuilt the disk on the same drive. It's been running fine since then. He suggested I create another post about this screen shot.

 

When I got the email notification of the failed drive I took a screen shot of the GUI. This screen shot was taken before I took any action of any kind. The Tower/Main GUI page is almost always open on my windows machine. This screen shot was taken within seconds of the email notification before I did anything but switching to this tab in Chrome.

 

On the attached screen shot you can see the six devices in the array all show up below in the Unassigned Devices section.  The array was running, I could still access the shares from the Win10 machine.

 

Also attached is the diagnostics.zip from after the restart.

tower-diagnostics-20160328-0015.zip

Update unRAID to latest stable then update any plugins that have updates. Then if it happens again let us know.