[ntp:questions] how did ntp service set the maxallowphaseoffset

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Tue Nov 19 08:41:25 UTC 2013


On 2013-11-18 23:05, xiaoniao112233 at gmail.com wrote:
>> On 2013-11-18 01:30, xiaoniao112233 at gmail.com wrote:> hello :

> But I have a question,how can I set this value,
> I just use it in a LAN to Synchonize the time in the LAN.
>So is that a stand-alone clients and servers.
>If it is ,which command should I use to change this value in LINUX OS.

I presume you refer to ntpd/tinker step?
This parameter alters when the daemon decides the system time offset is
too high to be disciplined by slewing the system clock rate, and it has
to fall back to step the time by the offset.
This will depend on the maximum system clock rate change headroom
available on each system, given the inherent frequency drift of each
system.

You should not need to change this parameter:
"tinker - modify sacred system parameters (dangerous)"!

On most systems, a step should only be necessary when you start the ntpd
daemon and the ntpd startup option -g --panicgate will allow a single
large adjustment to be made when ntpd has made its initial offset estimate
from other network time servers or a local hardware reference clock.

Before you consider changing this, you need to calibrate the inherent
frequency drift of *each* system's hardware clock crystal, to see
whether and what values might be feasible on *each* system.

To make a decision on whether this could be useful, please find a good
translation to your language of Linux man hwclock(8), adjtimex(8), ntpd(8),
and the NTP docs (or try Google Translate on the doc.ntp.org web site pages).

Someone else asked: what are you trying to do by changing this parameter?
The defaults have been set based on running and simulating different control
algorithms, settings, and scenarios.

Start by using the defaults and setup described in the "Quick Start" section
or set by your distribution in the default ntp.conf provided.

If nothing is provided use pool servers with an ntp.conf statement like:
pool asia.pool.ntp.org
or one of the country pools shown at http://www.pool.ntp.org/zone/asia
cn.pool.ntp.org, hk.pool.ntp.org, sg.pool.ntp.org, tw.pool.ntp.org.
-- 
Take care. Thanks, Brian Inglis


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