systemd – No logs if system starts with time set before it used to be during previous shutdown


I’m facing a strange situation when I have no logs at all if system starts with system time in past comparing to what it was during last boot. To be more exactly I have a single board computer the has no RTC onboard. The default system time is somewhere in 2018. If system booted without RTC or failed RTC, I will have no any logs in journald as well as collected by syslog-ng until NTP client fetches actual time leaving me completely blind. If I log something with logger command, nothing will appear. It looks like all messages prior the most recent logged ever before are discarded.

I don’t expect failed RTC with local NTP unavailable at the same time as a common scenario, but this still possible in case if main power failure.

I wonder if there is anything can be done so the system will log messages regardless they are in past?

The OS is Ubuntu 16.04.