It seems to be a specific part of SeaweedFS, i.e. the "filer+client" components. It will use a database or key-value store for metadata and a blob store for dat

It seems to be a specific part of SeaweedFS, i.e. the "filer+client" components. It will use a database or key-value store for metadata and a blob store for data, and expose that as a filesystem. The difference is that SeaweedFS has its own blob store ("volume server") while JuiceFS uses S3 (or some other protocols). SeaweedFS also decouples the server ("filer server") from the client ("mount" command or client libraries) while JuiceFS only has a single process, so the machine where you mount the filesystem talks to the metadata and data backends directly; this means you can't mount a filesystem on an untrusted machine if I understand correctly (you need full R+W access to the backends from the machine where you mount). You can see it as similar to `rclone mount`, which allows you to mount a remote S3 bucket locally. The difference is that JuiceFS is much faster and filesystem-like, by storing the metadata in a separate faster database and by chunking your files in the backend rather than storing files unchanged in the bucket.