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doc: update section on isolated networks

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Since the NTPv4 update, the detection of synchronization loops based on
the refid prevents a server to initialize its clock from its clients
after restart. Remove that part from the recommended configuration.
Also, mention the time smoothing feature.
This commit is contained in:
Miroslav Lichvar 2015-09-09 16:30:17 +02:00
parent 76d12ac136
commit d8b0a4a288
1 changed files with 10 additions and 19 deletions
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29
chrony.texi.in
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@ -694,40 +694,31 @@ support for this, in the form of the @code{manual} directive in the
configuration file and the @code{settime} command in the @code{chronyc} configuration file and the @code{settime} command in the @code{chronyc}
program. program.
If the master is rebooted, @code{chronyd} can re-read the drift rate The @code{smoothtime} directive (@pxref{smoothtime directive}) is useful when
from the drift file. However, the master has no accurate estimate of the clocks of the clients need to stay close together when the local time is
the current time. To get around this, the system can be configured so adjusted by the @code{settime} command. The smoothing process needs to be
that the master can initially set itself to a `majority-vote' of activated by the @code{smoothtime activate} command when the local time is
selected clients' times; this allows the clients to `flywheel' the ready to be served. After that point, any adjustments will be smoothed out.
master across its outage.
A typical configuration file for the master (called @code{master}) might A typical configuration file for the master (called @code{master}) might be
be (assuming the clients are in the 192.168.165.x subnet and that the (assuming the clients are in the 192.168.165.x subnet)
master's address is 192.168.169.170)
@example @example
driftfile @CHRONYVARDIR@/drift driftfile @CHRONYVARDIR@/drift
initstepslew 10 client1 client3 client6
local stratum 8 local stratum 8
manual manual
allow 192.168.165 allow 192.168.165
smoothtime 400 0.01
@end example @end example
For the clients that have to resynchronise the master when it restarts, For the clients the configuration file might be
the configuration file might be
@example @example
server master server master iburst
driftfile @CHRONYVARDIR@/drift driftfile @CHRONYVARDIR@/drift
logdir /var/log/chrony logdir /var/log/chrony
log measurements statistics tracking log measurements statistics tracking
local stratum 10
initstepslew 20 master
allow 192.168.169.170
@end example @end example
The rest of the clients would be the same, except that the @code{local}
and @code{allow} directives are not required.
@c }}} @c }}}
@c {{{ S:Dial-up home PCs @c {{{ S:Dial-up home PCs
@node Dial-up home PCs @node Dial-up home PCs