On 7.12.20 16.50, Adam Funk wrote:
> On 2020-12-07, Chris Green wrote:
>
>> Adam Funk  wrote:
>>> On 2020-11-29, Jim Jackson wrote:
>>>
>>>>> Your biggest problem will be deciding where to get your clock updates
from;
>>>>> do you open the Pi to the internet or run a timeserver on another
machine.
>>>>
>>>> Buy an RTC addon for those times when it reboots, and setup NTPD on it,
>>>> sync'ing from a couple of reliable internet timeservers. Then run the Pi
>>>> as your network time source.
>>>>
>>>> My home serving Pi is setup like that. Not that the RTC addon is used
>>>> much, as my Pi only reboots once in half a dozen blue moons! I do sync
>>>> the RTC from the system even day - so it isn't out by much if it does
>>>> reboot, until it gets ntp sync. ntp maintained system time is far far
>>>> more accurate than any RTC
>>>>
>>>> I used the AB electronics PiZero RTC
>>>
>>> Just out of curiosity, what significant benefits do you get from the
>>> RTC?  I have NTP running on mine, and the only anomaly I notice is
>>> this sort of thing in the `last` output:
>>>
>>> reboot   system boot  5.4.79-v7l+      Thu Jan  1 01:00   still running
>>>
>>> although `uptime` is correct and I can't find any '1970' or 'Jan' in
>>> any of the greppable log files.
>>>
>> 1st January 1970 is the "start of time" in the Unix world, that's why
>> the next "millenium bug" is somewhere about 68 years from 1970 when a
>> signed 32-bit count of seconds runs out.
>
> I understand why that's the magic reset date (which is why I was
> grepping for "Jan" as well as "1970") --- I was just wondering about
> what kind of situation needs the external clock so the time is
> accurate *before* NTP starts working.


The classic ntpd does not like to sync with a time that is
far off from the local time. I used ntpdate to set the local
time before starting ntpd up.

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-TV

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