Earlier quoted context omitted.
'Ephemeral' was/is the original Lustre design model. It was intended for high performance swap/scratch at Livermore with a short data lifespan - your higher priority bomb sim forces mine to roll out to disk and back in later, and that's it. Lustre, even today, isn't long term stable. The longer you leave data on it, the greater the probability of corruption - even silently.
I've seen Lustre backed with ZFS listed a few places. Is the idea here to help mitigate the possibility of corruption?
LLNL is the core force behind ZoL and it's primarily them who use ZFS-backed Lustre.