On Sun, Nov 6, 2011 at 2:13 PM, Danny Mayer <[email protected]> wrote: > On 11/4/2011 7:27 PM, Nathan Kitchen wrote: > > I'm curious about some behavior that I'm observing on a host running > > ntpd as a client. As I understand it, configuring a local reference > > clock--either an undisciplined local clock or orphan mode--shouldn't > > help me, but I see different behavior when I do have one. In > > particular, when I'm synchronizing after correcting a very large > > offset, I synchronize about 2x faster in orphan mode than with no > > local clock, and with an undisciplined local clock I don't even fix > > the offset. > > > > I'm curious about whether this difference should be expected. > > > > I'm using the following configuration in all cases: > > > > driftfile /persist/local/ntp.drift > > server 172.22.22.50 iburst > > > > My three different configurations for local clocks are the following: > > > > 1. No additional commands > > > > 2. tos orphan 10 > > > > 3. server 127.127.1.0 > > fudge 127.127.1.0 stratum 10 > > > > In all three cases, my test has these steps: > > > > 1. Stop ntpd. > > 2. Set the clock to 2000-1-1 00:00:00 (that is, more than 10 years ago). > > 3. Run ntpd -g. > > 4. Check that the 11-year offset is corrected. > > 5. Wait for synchronization to the time server. > > > > With either configuration #1 (no local clock) or #2 (orphan mode), the > > offset is corrected quickly: 4 and 13 seconds, respectively. With > > configuration #3 (undisciplined local clock), it fails to be corrected > > within 60 seconds. > > In case #3 that's expected if there are no servers to get the correct > time. What else would you expect? Where would it get it's time from?
In case #3, as in the other cases, the configuration includes the server 172.22.22.50. > > After the offset is corrected, configuration #1 takes 921 seconds to > > synchronize to the server. Configuration #2 takes 472. > > > > First, correcting the offset is the major concern. After that figuring > out the frequency changes need to be calculated with additional packets > being received and that takes time. It needs to have enough of them to > do the calculation. Why would it take fewer packets with orphan mode enabled (and no peers) than with no local clock? -- Nathan _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
