We see similar results using JuiceFS [1], are glad to see that another player has moved on the same direction with us, since JuiceFS was released to public in 2017, and is available on most of public cloud vendor.

The architect of JuiceFS is simper than HopsFS, it does not have worker nodes (the client access S3 and manage cache directly), and the metadata is stored in highly optimized server (similar to NN in HDFS, can be scaled out by adding more nodes).

JuiceFS provide POSIX client (using FUSE), and Hadoop SDK (in Java), and a S3 gateway (also a WebDAV gateway).

[1]: https://juicefs.com/docs/en/metadata_performance_comparison....

Disclaimer: Founder of JuiceFS here