On 10/02/2020 23.20, Alexey Dobriyan wrote:
SK hynix is going to ship ZNS device with zone size not being power of 2. Signed-off-by: Alexey Dobriyan (SK hynix) <adobriyan@xxxxxxxxx> ---
Nack from here as well. The power of 2 is a strict requirement. All SMR HDDs Zone Sizes are a power of two, and ZNS SSDs should be as well if they want Linux eco-system support.
The ZNS specification is specifically written to accommodate this. It has two type of zone sizes, the Zone Size (which is what should be a power of two) and the Zone Capacity (that is the writable capacity of the zone). For Linux support, your ZNS SSD implemention must have a zone size that is power of two, and instead use the Zone Capacity field to be the "Zone Size" that you have now. Then it works as expected, making both the host and device happy. The host gets power of two, and device can communicate the non-power of two writeable LBAs within the zone.
Best, Matias
