[ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.

David Lord snews at lordynet.org
Tue Mar 13 21:39:28 UTC 2012


Ron Frazier (NTP) wrote:
> On 3/13/2012 2:40 PM, Chris Albertson wrote:
>> On Tue, Mar 13, 2012 at 9:52 AM, Ron Frazier (NTP)
>> <timekeepingntplist at c3energy.com>  wrote:
>>   
>>> Hi all,
>>>
>>> I just woke up to a 50 SECOND clock error.  Prior to the error, with 
>>> my PC
>>> locked into the GPS and the internet servers noselected, here's what my
>>> peerstats looked like.  Baseline is the GPS.  Colored lines are internet
>>> servers.
>>>
>>> http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg
>>>      
>> Looks to me like that GPS, maybe lock lock and was able to "coast" on
>> hold over for a while then fell off a cliff.     If you have a log of
>> satellite  signal to noise ratios you might be able to figure out why.
>>
>> The internet servers appear to be 100% reliable seeing as they all agree.
>>
>> These kinds of things are why some hobbysts end up buying multiple GPS
>> (different brands)  Otherwise it is hard to sort out a GPS firmware
>> bug from a solar storm or just that there were not sats visable to
>> your indoor antenna for a few minutes
>>
>> I think your goal is to learn about all of this so these problems are
>> a good thing.  No one learns much from working systems.   But if the
>> goal is a reliable NTP server, the pool NTP servers can't be beat
>> except by a good timing mode GPS, that has good self diagnostics and
>> PPS.  The self diagnostics part is important
>>    
> 
> The link you quoted just now is not the one that bugs me so much today.  
> This one is the one that bugs me today, where my clock was stepped by 50 
> seconds for some reason.
> 
> http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg

I'm on a text mostly system so why do you require me to use
a web browser to help you?

What is your current ntp.conf, ntpd version, operating system
and response of "ntpq -crv -p" after ntpd has had at least
a day to stabilise?

Not so long ago you posted that you had an offset within
+/- 6 ms but didn't give any evidence. Response from
"ntpq -crv -p" or better a day from peer_summary or couple
of days from loop_summary would be enough.


David


> When I get the Sure board, I plan to hang it on the pc in tandem with 
> this GPS and compare.
> 
> Sincerely,
> 
> Ron
> 
> 



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