[ntp:questions] Pool server gone wild

Terje Mathisen terje.mathisen at tmsw.no
Fri Feb 20 11:38:50 UTC 2015


Roger wrote:
> On Fri, 20 Feb 2015 10:15:31 +0100, Terje Mathisen
> <terje.mathisen at tmsw.no> wrote:
>
>> Rob wrote:
>>> Roger <invalid at invalid.invalid> wrote:
>>>>       http://www.pool.ntp.org/scores/90.155.73.34
>>>>
>>>> How does one alert an operator that their server is sick?
>>>> Checking back through my peerstats I see that last entry
>>>> which was okay was 2015-02-16 15:08:56.
>>>
>>> There is no need.  The pool system has sent a mail to the operator
>>> and when he apparently does not react it is not a problem because
>>> the server will have been removed from the pool anyway.
>>>
>> You are of course correct, I would just add a single small caveat:
>
> OK, Rob, thanks for that.
>
>> If you are using an older version of ntpd which doesn't support the pool
>> directive, then you would be stuck trying to access such a server until
>> you restart ntpd.
>>
>> With something like 'pool pool.ntp.org' in your ntp.conf file the ntpd
>> process will pick the first N (10) servers returned from DNS, then once
>> every hour it will redo the DNS lookp, the two worst-performing current
>> servers will be removed and a pair of new ones will be used to replace them.
>
> I'm using 4.2.8p1 (compiled using gcc 4.8.2 and binutils 2.23,
> if those are important) and "pool uk.pool.ntp.org" as the only
> selection line.

The UK pool might have too few servers.

What does your 'ntpq -p' look like?

If you have less than 10 servers then none of them will be dropped 
afair, but you can tweak this limit with a fudge command.

Terje
>
> The server was still in the peerstats at 18:25 the following day
> when I did a reboot. So, after approximately 27 hours, ntpd
> hadn't dropped it. Obviously, my system isn't performing as you
> say it should. Can you, or anyone else, provide a clue as to how
> I might determine if my system is a fault or if there is a bug
> in the ntpd code?
>
>> I.e. as long as you use the pool properly there is no need to worry
>> about servers coming and going, or even individual servers that become
>> falsetickers.
>
> When I first tried 4.2.8 I noticed the "soliciting" lines and
> that occasionally a server didn't get used. I've never noticed
> ntpd dropping a server once it had started using it but this is
> the first time that a server has been so obviously wrong that I
> would have wanted it dropped/replaced.
>


-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"



More information about the questions mailing list