[ntp:questions] ntp.drift file

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Thu Dec 9 03:36:37 UTC 2010

In article <AANLkTinTLFbOJ+qcWC1G8n-Oy88_YyPcuBOHXS2i5gwX at mail.gmail.com>,
 Dave Hart <davehart at gmail.com> writes:

> Newer versions are more adaptive depending on how much the value is
> changing, but historically it was once an hour, and I believe in the
> latest ntp-dev it is no more often than once per hour, less if the
> value isn't changing much.

ntp-dev has a nonvolatile parameter in ntp.conf.
from miscopt.html

nonvolatile threshold
    Specify the threshold in PPM to write the frequency file, with
  default 0.1 PPM. The frequency file is inspected each hour. If the
  difference between the current frequency and the last value written
  exceeds the threshold, the file is written and the threshold becomes
  the new threshold value. If the threshold is not exceeded, it is
  reduced by half. This is intended to reduce the frequency of unnecessary
  file writes for embedded systems with nonvolatile memory.

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