this has happened twice to me now and both times since i moved to the SD card solution..
I'm running a gen8 micro server, which i moved the OMV install from an SSD on the OD port to teh inbuilt SD card and using the folder2ram plugin, i also have a USB drive connected to a usb3 port.
i noticed that if i look at the physical drives or smart tabs i get a communication error and then at some point the servers stops responding, the fans start pulsing between high and low over a one minute period and nothing can be done except a hard power off.
Since powering back on, and also this happened the last time, there is missing statistics, like a whole weeks worth missing...
is the SD card filling up or some thing or is possible the USB drive ?