My logs are also being spammed with this:
Dec 31 17:29:53 Fileserver emhttpd: read SMART /dev/sda
The funny part is /dev/sda is an external USB3 enclosure mounted via Unassigned Devices. SMART data will never be available for that device.
I'm still seeing no logging whatsoever with 6.9.0-rc2 (started with 6.9.0-beta25 I believe). The log button (upper-right console toolbar button) opens an empty window. DMESG does have output, however. The "/var/log/messages" file is empty, as is "/var/log/syslog".