[ntp:questions] Pool server gone wild

Roger invalid at invalid.invalid
Fri Feb 20 12:45:54 UTC 2015


On Fri, 20 Feb 2015 12:38:50 +0100, Terje Mathisen
<terje.mathisen at tmsw.no> wrote:

>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.

Thank you for your fast response. A dig of uk.pool.ntp.org gives
4 addresses. I've changed my ntp.conf to have 4 pool lines
selecting 0.uk, 1.uk, 2.uk, and 3.uk (each of these gives 4
addresses, presumably all different). Restarting ntpd it
solicited 7 servers all of which show up with "ntpq -p" (along
with the four pool lines).

After about 11 minutes it has dropped one, leaving 6 servers.
I'll continue to monitor and report back.
-- 
Roger



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