[CentOS] ntp will not drift to correct time

[David G. Miller]

Tom Brown <tom at ...> writes:

> 
> Hi
> 
> On 5.3 i have a situation where some boxes have been 3 or 4 seconds out 
> and restarting ntpd has fixed the issue.
> 
> What i dont understand is why the clocks did not drift to the correct 
> time when the config seems correct in that restarting ntp did correct 
> the time.
> 
> Is there something 'special' i need to do in order for the drift to work?
> 
> $ cat /etc/ntp.conf
> restrict        default ignore
> restrict        127.0.0.1
> restrict        10.0.0.0 mask 255.0.0.0 nomodify notrap
> server        server01
> server        server02
> fudge           127.127.1.0 stratum 10
> driftfile       /var/lib/ntp/drift
> broadcastdelay  0.008
> keys            /etc/ntp/keys
> 
> # cat /etc/ntp/step-tickers
> server01
> server02
> 
> any clues?
> 
> thanks
> 
>From the ntpd documentation:

Note: Since the slew rate of typical Unix kernels is limited to 0.5 ms/s, each
second of adjustment requires an amortization interval of 2000 s. Thus, an
adjustment as much as 600 s will take almost 14 days to complete.

By design, ntp takes a while to correct a clock.

Cheers,
Dave