How about Lustre and Ceph? Any chance to adjust those filesystems for storagenode purposes or are they rather a far cry for us? Lustre supports both ext4 and zfs but it might not be an easy setup. Ceph is supported by Canonical LXD / MicroCloud but its default setup is rather not suitable straight out of the box. Disclaimer: I do see some potential benefits but those filesystems were designed for rather large environments. Anyway, apart to NFS, are you maybe considering doing some testing on them in the foreseeable future @IsThisOn? :- )