Jimmy ntp wrote: > Hi, > I'm consistently seeing offsets between +- 6 ms on my Windows servers. > For the same hardware running Linux, NTP behaves great (+- 500 us offset) > but on Windows it is bad. Also the same version of Windows on AMD procs is > behaves great. > > Hardware: > HP ProLiant DL360 G5 > * 2 Quad-Core Intel(R) Xeon(R) Processor E5450 > * 8 GB of memory > > Software: > * Windows 2003 > * ntp-4.2.0a > > Here is ntp.conf: > ======================== > server 192.168.10.5 burst iburst minpoll 4 maxpoll 6 > server 192.168.10.6 burst iburst minpoll 4 maxpoll 6 > server 10.10.10.10 burst iburst minpoll 4 maxpoll 6 > server 10.10.10.11 burst iburst minpoll 4 maxpoll 6 > server 10.10.10.12 burst iburst minpoll 4 maxpoll 6 > server 10.10.10.13 burst iburst minpoll 4 maxpoll 6 > server 10.10.10.14 burst iburst minpoll 4 maxpoll 6 > server 10.10.10.15 burst iburst minpoll 4 maxpoll 6 > ======================== > > % ntpq -np > remote refid st t when poll reach delay offset > jitter > ============================================================================== > *192.168.10.5 .GPS. 1 u 44 64 377 0.905 -4.274 > 0.656 > +192.168.10.6 .CDMA. 1 u 1 64 377 18.731 -6.324 > 1.915 > +10.10.10.10 192.168.10.5 2 u 29 64 377 0.399 -5.357 > 0.535 > -10.10.10.11 192.168.10.5 2 u 4 64 377 0.352 -6.036 > 0.175 > -10.10.10.12 192.168.10.5 2 u 34 64 377 0.397 -5.200 > 0.642 > -10.10.10.13 192.168.10.5 2 u 1 64 377 0.498 -5.910 > 1.410 > -10.10.10.14 192.168.10.5 2 u 2 64 377 0.376 -6.069 > 1.450 > -10.10.10.15 192.168.10.5 2 u 1 64 377 0.335 -5.132 > 1.465 > > > Have any one seen this issue? Any advice? Thanks in advance.
Remove the "burst" and "minpoll 4 maxpoll 6" from all your server statements! Restart ntpd and be sure to use the -g switch. Burst is a special purpose keyword intended for situations in which your system makes a dial-up telephone connection to a server three or four times a day. Using the burst keyword in any other situation is considered abusive! The default values of MINPOLL and MAXPOLL (six and ten) are correct for virtually all situations and should be left intact! My non-mathematical explanation is that the shorter poll intervals allow large errors to be corrected quickly and the longer intervals allow small errors to be corrected very accurately. NTPD adjusts the polling interval within the range defined by MINPOLL and MAXPOLL as needed. See RFC-1305 for the math. If you are good at advanced math and control systems theory, you may find RFC-1305 enlightening! Also note that Windows is a difficult environment! The clock ticks at something like 17 millisecond intervals. If you really need/want time to the nearest microsecond, Windows is a poor choice of O/S. There is some way to interpolate between ticks which has been mentioned here from time to time but I don't recall what it is. I have no need for time to the nearest microsecond on my Windows systems and have not tried to memorize the details! _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
