[ntp:questions] Is this normal?

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Thu May 13 05:17:34 UTC 2010

In article <C430DA47D51D0C4B940F6928BAE21F4626A3F16590 at SBKMXSMB06.win.dowjones.net
 "Russell, David" <David.Russell at dowjones.com> writes:
> The device is a piece of networking equipment and so I doubt that the crystal
> is temperature controlled but since it is in a data center the temperature
> and power demand is steady.

> If you could see the graph you would see that it seems to oscillate around
> -3.05 us/s over a 24 hour timeframe. The graph has a pretty nice looking 
> sine wave with a 12 hour period.  I was expecting that if the "true" drift
> rate were -3.05 then NTP would converge upon that value.  Are you saying
> that this oscillation is typical for non-temperature (cheap) crystals or
> should the drift look more random?

The drift follows temperature.  Do you have any way to measure the temperature?

> Any thoughts on validating a black box NTP process?

Setup NTP on another box and tell that box to use the black-box as a server.
Use "noselect" if you want to make sure it won't try to sync to that system.
Then turn on loopstats and peerstats.  That will give you lots of data to
look at.

> I had not realized until I sent out the email that no attachments are allowed.
> Is there a way to share a graph?

Put it on the web someplace and send a URL.

These are my opinions, not necessarily my employer's.  I hate spam.

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