Hi,
If a supported FAS platform (FAS8040, FAS8060, FAS8080) is intended to be "converted" into an AFF platform, there are boot loader arguments that need to be set in order for the feature within ONTAP to be enabled. The following KB should help: https://kb.netapp.com/support/index?page=content&id=1015157&locale=en_US
Note that the assumption here is to only enable All-Flash FAS optimizations but does not make any changes to root partitioning as if if was a net-new AFF environment.
If that is the desired end-result, this KB can help: https://kb.netapp.com/support/index?page=content&actp=LIST&id=1015004
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