AFAIK, flashcache is not used when a flashpool aggregate is in use (at least for the flashpool accelerated aggregate).
It looks like the latest FAS line now includes NVME flashcache in all models. I wonder if the same limitation exisit?.
It would seem odd to include fashcache in every model when in most models it would go unused (ie I imagine most units sold are hybrid or AFF).
Does anyone know of the interplay between the new NVME flashcache and Flashpool is different with ontap 9.1 and these new units?