troubleshooting_ntp

troubleshooting_ntp.markdown

@@ -21,4 +21,30 @@ Use these commands as root on the workstation:
 
 With this the time of the system clock will be set every 5 minutes and synchronized with the hardware clock.  This is essentially the same that ntpd and the kernel are doing except that it works even when ntpd fails to synchronize with the time servers.
 
+Give it at least a few hours or better a couple of days.
+
 With the log file ''/var/log/ntpdate'' you can get an estimate about the drift of the system clock.
+
+==== Calibrating the System Clock ====
+
+Use these commands as root on the workstation:
+
+  /etc/init.d/ntp stop
+  rm /var/lib/ntp/ntp.drift
+  adjtimex --tick 10028 --freq -1456356
+  ntpdate -s time1.ethz.ch ; /etc/init.d/ntp start
+
+Then watch the offset to the time servers converge or drift apart:
+
+  watch ntpq -p
+
+If the offset drifts rather than converges then try other values for adjtimex, e.g.:
+
+  adjtimex --tick 9944 --freq 2912711
+  adjtimex --tick 9972 --freq 1456356
+  adjtimex --tick 10000 --freq 0
+  adjtimex --tick 10028 --freq -1456356
+  adjtimex --tick 10056 --freq -2912711
+
+Take one of these or calculate some numbers by yourself according to the ajdtimex(8) man page at the end.  You may also find it convenient to use the Javascript form on [http://www.ep.ph.bham.ac.uk/general/support/adjtimex.html]
+