I has just checking NS0-182 practice exam (https://www.brainshark.com/netapp/NS0-182-PRACTICE link from NetApp webpage) and one of the question was how to configure additional write cache for SAS drives.
To my surprise the correct answer was to install Flash Cache NVMe module.
I was thinking Flash Cache is read cache only and Flash Pool provides write cache for overwrites. Did something change recently? Can't find any evidence...