[ntp:questions] Re: ntpd, boot time, and hot plugging

David L. Mills mills at udel.edu
Sat Feb 5 17:07:05 UTC 2005


Alain,

I did the same thing as you, but ntpd -gq with 8 servers and iburst set 
the clock in 8 seconds, not 45. This includes DNS. Did yours stall in 
DNS? Each of the g, q and x option descriptions has a sentence that 
mentions that the option can be used in conjuntion with the other two.

The ntpd polls the servers in parallel, but offsets to avoid bunching. 
Note ntpd uses a two-second poll interval to avoid violating the KoD 
rules. The ntpdate uses one second, which result up to half the polls 
can be ignored and (if configured - our severs are) a KoD sent.

The Corps is working on a SNTP replacement for ntpdate, presumably 
compliant with the ID I mentioned earlier. I can't tell you how relieved 
I would be when this comes to pass and evil ntpdate can be finally torched.

I'm really nervous about the kit of knobs now in ntpd which may be ripe 
for misinterpretation, misuse and misunderstood documenation. Every new 
"feature" increases the complexity and fragility of the program and 
consumes lots of my time in testing, documentation and mail 
correspondence. The IETF task force now studying the specification issue 
should take up the issue of a standard set of parameters selectable at 
configuration time which would cater to whatever the community wants.

Dave

Alain wrote:
> Hi all,
> 
> I made some tests with extreme bad initial clocks:
> 
> # date --set "01/01/00 00:00"
> Sáb Jan  1 00:00:00 BRDT 2000
> # ntpd -gq
> ntpd: time reset 160871283.056670s
> 
> This does works great, but takes 45 seconds (8 servers with iburst).
> This -gq combination was not clear in the docs, now that I know about it 
> I read it again and in fact it is there, but I did read it many times 
> and missed just something.
> 
> ntpdate with 5 servers 3 seconds
> ntpdate with 8 servers 4 seconds
> 
> It looks like ntpdate does most things in parelel.
> 
> Per Hedeland escreveu:
> 
>> If your latest ntpd tweak knobs can really achieve the low-quality-but-
>> really-quick time setting that ntpdate provides, *and* the combination
>> of knob settings needed for that is codified into another ntpd option
>> (--impatient maybe?:-), I think ntpdate can finally be laid to rest.
>> Requiring a separate config file just for this boot-time setting, with
>> parameters and values that are even more esoteric to the average user,
>> is really a show stopper IMHO.
> 
> 
> Agreed. Maybe the "twek knobs" + "minpoll=1" (this look similar to what 
> ntpdate uses) could be command line or just temporary and disabled after 
> the initial time set. I hope that whatever replaces ntpdate is 
> aproximately as fast (say like <5s)
> 
> Thanks for your patience again,
> Alain



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