On Friday 16 December 2005 3:10 am, Carl Hartung wrote:
4. When the above process is completed, the client is effectively synced to the server. This makes two things possible: a) the hardware clock drift can be accurately measured and, b) that drift can be compensated for in software until the hardware clock is due for it's next adjustment (cron job? reboot?)
It's the ongoing compensation process that I'm wondering about, not the initial calculations. Presumably not only does the hardware clock drift, but the amount of drift itself drifts. Moreover, the tiniest inaccuracy in the drift value will accumulate over time. The natural way to handle this, I'd think, would be to check the external servers hourly, say (that shouldn't impose too great a load on them) and then modify the drift value accordingly. In between, use the drift data to nudge the hardware clock to the correct value. But I can't tell from the ntp docs I've looked at if this is what's supposed to happen -- or if not, what really does happen. My drift file hasn't been modified for the last two days, according to "ls -l". Paul