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From: Dave on 7 May 2008 03:45
David Woolley wrote:
> Dave wrote:
>> Looking at the logs on my Sun Blade 2000 running Solaris 10, I see
>> numerous occasions on which the time has been stepped. Looking at the
>> few only (today, 1/5/2008), I see it was stepped around +0.3 sec at 3
>> AM, then -0.4 at 4:30 am, then half an hour later at 5am it was moved
>> -0.6 sec, then 40 minutes later it is moved another -0.6 sec. Since
>> then (its now 1:30 pm), it has not changed.
>
> Positive and negative steps which approximately balance each other
> indicate a heavily loaded link with variable and asymmetric propagation
> delays. Apart from local servers, or your Rubidium PPS, or reducing the
> traffic, the other solutions are to apply and get the ISP to apply
> traffic shaping to prioritise NTP traffic, or to use the tinker huff and
> puff option, noting the health warnings attached to it.


I've changed to local servers as suggested

server 0.uk.pool.ntp.org
server 1.uk.pool.ntp.org
server 2.uk.pool.ntp.org
server 3.uk.pool.ntp.org


broadcast 224.0.1.1 ttl 0


statistics loopstats
statistics peerstats
driftfile /var/ntp/ntp.drift
statsdir /var/ntp/ntpstats/
logconfig =all


and it has made no significnat difference. (I've just added the lines

statistics loopstats
statistics peerstats

but these were not in the config file when I collected this data.

May 6 06:11:09 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.224887 s
May 6 06:38:22 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.669705 s
May 6 07:18:42 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.253622 s
May 6 07:47:00 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.405924 s
May 6 08:39:43 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) -0.277034 s
May 6 09:13:53 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.144278 s
May 6 11:10:18 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.487560 s
May 6 13:58:14 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) 0.150888 s
May 6 15:02:22 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) -0.243454 s
May 6 16:03:35 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) -0.284934 s
May 6 21:35:00 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) -0.369864 s
May 6 22:39:50 kestrel xntpd[3604]: [ID 774427 daemon.notice] time
reset (step) -0.396888 s


After added the lines

statistics loopstats
statistics peerstats

I stopped and started the deamon (I guess refreshing might do), and get:

May 7 08:35:14 kestrel ntpdate[24721]: [ID 558275 daemon.notice] adjust
time server 78.129.142.80 offset -0.002180 sec


From: Dave on 7 May 2008 03:47
Dave wrote:
> David Woolley wrote:
>> Dave wrote:
>>> Looking at the logs on my Sun Blade 2000 running Solaris 10, I see
>>> numerous occasions on which the time has been stepped. Looking at the
>>> few only (today, 1/5/2008), I see it was stepped around +0.3 sec at 3
>>> AM, then -0.4 at 4:30 am, then half an hour later at 5am it was moved
>>> -0.6 sec, then 40 minutes later it is moved another -0.6 sec. Since
>>> then (its now 1:30 pm), it has not changed.
>>
>> Positive and negative steps which approximately balance each other
>> indicate a heavily loaded link with variable and asymmetric
>> propagation delays. Apart from local servers, or your Rubidium PPS,
>> or reducing the traffic, the other solutions are to apply and get the
>> ISP to apply traffic shaping to prioritise NTP traffic, or to use the
>> tinker huff and puff option, noting the health warnings attached to it.
>
>
> I've changed to local servers as suggested
>
> server 0.uk.pool.ntp.org
> server 1.uk.pool.ntp.org
> server 2.uk.pool.ntp.org
> server 3.uk.pool.ntp.org

I meant to add that perhaps an overloaded network is the problem. The
machine only has a 256 kb/s uplink (1024 kb/s downlink), and is used as
a web server for a small number of little used domains. Perhaps this is
putting too much strain on it. I occasionally download large files (like
iso images of Solaris), so I'll check if things get worst next time I do
that.
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