Surely for hardware being lugged around on the back of a truck, potentially exposed to whatever heat, humidity, vibration, etc - redundancy becomes a vital comp

Surely for hardware being lugged around on the back of a truck, potentially exposed to whatever heat, humidity, vibration, etc - redundancy becomes a vital component of the design. I would expect at least 2-3x replication for every byte written. Depending on how sealed the container is, they may not want to physically extricate failed drives and merely mark them as unavailable for use.