HM (Host Managed) SMR has no “dumb mode” - HA (Host Aware) SMR has a fallback.
Linking to a previous post of mine on this:
At present HM-SMR drives work on a granularity of 256M. Think of the problems of trying to use ashift=9 on devices that should be ashift=12 - so 512b into 4K - and then amplify it massively as SMR zones are effectively ashift=28
