I ran the following two parameters in my cron script so this is always set after the RAID device is mounted :
#Set Reboot on Kernel Panic
echo 30 > /proc/sys/kernel/panic
echo 1 > /proc/sys/kernel/panic_on_oops
I then triggered a kernel panic as per https://fedoraproject.org/wiki/How_to_use_kdump_to_debug_kernel_crashes (Step 2) and then waited and the NAS did end up rebooting by itself, so it might be possible this is a “workaround” for a hung NAS. This is by no means perfect as it is still putting the disks in an inconsistent state.
One thing which I am not sure if WD have considered is the kernel level. Currently it is 3.10.39, but don’t remember this issue happening when I original got the NAS about 2+ years ago. If the kernel has been updated in the meantime, perhaps this has introduced a bug which now causes kernel panics. Compiling a newer kernel for the device could possibly help ?
Perhaps someone from WD Staff or a moderator could comment. Only way to get further is to try and get a serial console working on the EX4100 or to see if something like netconsole could be compiled and installed onto the EX4100.