xntpd.1m (2010 09)

xntpd(1M) xntpd(1M)

: Previous time adjustment incomplete; residual -0.020623 sec

But this does not mean that your system clock has been stepped. Only the

NTP daemon process has seen

a step in its notion of the current time (and this will be passed on to clients). The system time is being

gradually adjusted in a series of

SLEW maneuvers, and the

SLEW rate is quite limited. Be warned that

it can take a long time for the system clock to reach nominal correctness, and much longer to stabilize.

Each cpu model is unique, but the maximum slew rate is typically about 40 milliseconds per second.

Thus a

SLEW adjustment of 411 seconds will take over 10,000 seconds (about 3 hours) to complete. A

better approach would be to run the

ntpdate command once at system startup, and accept the one

STEP change that comes with it. Then start the

NTP daemon process xntpd and it will never make a

STEP as long as your connection to the timesource is good. This method also overcomes the 1000 seconds

problem. The

NTP startup script /sbin/rc2.d/S660xntpd

will do this automatically if you

conﬁgure the

NTPDATE_SERVER

variable in /etc/rc.config.d/netdamons

. A properly

conﬁgured

NTP hierarchy with average networking (say 10Base-T) can run for years without ever mak-

ing a STEP change.

AUTHOR

xntpd was developed by Dennis Ferguson at the University of Toronto.

Text amended by David Mills at the University of Delaware.

FILES

/etc/ntp.conf The default conﬁguration ﬁle

/etc/ntp.drift The default drift ﬁle

/etc/ntp.keys The default key ﬁle