Puzzling clock offset spikes
paul at anastrophe.com
Thu Jul 5 17:22:44 UTC 2018
On 7/5/18 10:13, Gary E. Miller wrote:
> Yo Paul!
> On Thu, 5 Jul 2018 09:53:05 -0700
> Paul Theodoropoulos <paul at anastrophe.com> wrote:
>>> You are runnning USB on a timekeeping RasPi? I stopped doing that
>>> when I noticed it wrecked havok with my measurements. Unplug!
>> I attach a microSD card in a USB adapter in order to perform backups,
>> but I do only intermittently - every few days to a week or so. I
>> could probably leave it attached to the ntpVIZ Raspi 1 and rsync over
>> the LAN though; I should probably do that, then I can back up on a
>> more formal schedule.
> That's unrelated to your issue, the timescale is very different.
Right - however, it does make much better general administration sense
than randomly plugging in an adapter to make backups. Backups nightly
via rsync is the only rational path.
>>> Of course the ethernet goes through USB on the RasPi, so minimize
>>> ethernet usage too.
>> Latency, jitter, etc, are terrible over wifi, and I have pretty good
> Yup. I avoid the WiFi on RasPis if at all possible.
Well, I just looked up the specs on the raspi 3 B+, and apparently the
wifi has been bumped up in spec quite a bit compared to my old raspi 1,
so I should at least test it out and see.
>> When I monitor the netdata graphs in realtime over the WAN,
>> there's no visible change to the metrics, and that generates a lot of
>> https traffic, so I don't think that's it.
> Is your WAN on WiFi or Ethernet?
Connection from raspi to wan is ethernet, one switch between it and the
>> That said, latency and jitter were terrible when I first got my raspi
>> 1 a couple of years ago; I've never tried it on the 3, so perhaps
>> wifi on the raspi 3 might not suffer those issues; I will have to
>> look into that. It'd be nice to be able to untether the little devil
>> anyway, so I could easily relocate it elsewhere in the house where
>> ambient temps might be smoother. I will check it out!
> WiFi ethernet extenders are now cheap.
Right, I have a couple already, but I do have couple of locations close
to the main AP that I can try it out. I'll give this all a whirl later
this afternoon. Thanks Gary!
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