Apparently, the OS kernel can hide all the quirks of ZNS and expose it as a traditional filesystem. But how much of the benefit will disappear if you do this?
As far as I know, the main target use case is not for OS kernel to use it as a backend for traditional filesystem. This will just move the responsibility for handling the flash block management from a highly specialized SSD controller with HW accelerators to an inefficient general purpose host CPU. Some high-end SSD have several GB of DRAM to keep track for flash block managements. I won't want my host OS to use large chunk of RAM just for flash management.
The main target application for ZNS is for certain data center applications that usually performs large sequential block writes. This will significantly reduces many flash management overheads on the storage stack but the application will need to be aware for the ZNS/SMR behavior.
So, the title of the OP is a little incorrect. It is not an evolution for SSD but more like an additional feature for certain specialized application. It is not meant to replace current conventional SSDs.
PS: I work for WD SSD but not involve in ZNS.
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