Am 04.02.2015 um 06:00 schrieb Stefan Fritsch: > On Wednesday 04 February 2015 01:41:14, Michael Biebl wrote: >> Am 31.01.2015 um 10:19 schrieb Stefan Fritsch: >>> severity 755722 serious >>> retitle 755722 systemd must sync systemclock to RTC on shutdown >>> thanks >>> >>> >>> Systemd must make sure that the system clock does not go >>> backwards, >>> which causes all kinds of problems, with file systems and with >>> other software. To achieve that, systemd has to sync the system >>> time to RTC on shutdown. Upstream's argument that the system time >>> may not be more accurate is completely unrelated to this issue. >> >> Upstream argues, that whoever changes the clock, should also make >> sure to sync that to the RTC if so desired. E.g. if you change the >> time using the builtin timedatectl command, it will make sure the >> RTC is synced. > > There is also natural drift between the system clock and the RTC. Who > is supposed to account for that? On a system with an uptime of several > months, the drift may be large enough to cause the time to go > backwards at a reboot.
Running hwclock --systohc on shutdown does not solve the time skew problem. You could use hwclocks drift calculation and call hwclock --adjust e.g. via a cron job. That is ugly though and it get's easily confused in multi-boot environments. A better alternative is NTP. Incidentally, systemd ships systemd-timesyncd, a SNTP client, which can easily be enabled via "systemctl enable systemd-timesyncd.service" and we are discussing about shipping it enabled by default. -- Why is it that all of the instruments seeking intelligent life in the universe are pointed away from Earth?
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