[ntp:questions] Wrong time after changing hardware

Jan Ceuleers janspam.ceuleers at skynet.be
Fri Jul 27 07:10:14 UTC 2007


Harlan Stenn wrote:

> A drift file is useful, and the point you seem to be missing is that there
> is a class of users who want it written, but as infrequently as possible.

Harlan,

I am among the people who run ntpd on an embedded platform that only has 
flash memory as non-volatile storage.

The way I deal with the drift file is:

- I create a small RAM disk and point /tmp and /var at it

- As part of the boot process /var is initialised from a flash-based 
directory tree

- Ntpd is told to expect/create its drift file somewhere in /var; the 
flash version of the file contains a sensible value for the particular host.

The purpose of the drift file in this setup is principally as a means of 
monitoring ntpd: goodness ensues from finding that the drift file 
contains a value that is close to the expected value. Since reboots are 
extremely infrequent I might do without the initial value, but it works 
and it does seem to improve convergence so why not.

Cheers, Jan




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