[ntp:questions] Re: ntpd, boot time, and hot plugging
Tom Smith
smith at cag.lkg.hp.com
Fri Feb 4 18:59:39 UTC 2005
Brad Knowles wrote:
> At 4:21 AM +0000 2005-02-04, Tom Smith wrote:
>
>> # time ntpd -gq [13 servers in ntp.conf]
>> ntpd: time slew -0.000373s
>>
>> real 1m43.03s
>> user 0m0.10s
>> sys 0m0.60s
>
>
> Yes, but what does that ntp.conf look like? Are you using iburst?
> Any authentication? Manually setting minpoll and/or maxpoll? Did you
> have a good drift file to start with?
>
> You need to provide some more specifics before you can make an
> attempt to compare this to ntpdate.
>
>> # time ntpdate -b [three selected servers]
>> 3 Feb 22:44:45 ntpdate[186032]: step time server [IP address] offset
>> -0.000157 sec
>
>
> Not comparable. You need to include all thirteen servers before
> this could potentially be considered comparable.
>
As you wish...
# cat /etc/ntp.drift
-2.653
# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
LOCAL(1) LOCAL(1) 5 l 41 64 377 0.000 0.000 0.004
[IP.255] 0.0.0.0 16 u - 64 0 0.000 0.000 4000.00
-[name] .TRUE. 1 u 468 1024 377 12.741 -0.950 0.092
-[name] .WWVB. 1 u 470 1024 377 1.388 1.015 1.216
-[name] [name] 2 u 135 256 337 0.004 -0.490 0.440
-[name] .GPS. 1 u 997 1024 377 88.936 0.153 1.854
+[name] .GPS. 1 u 603 1024 377 88.146 0.546 0.119
*[name] .GPS. 1 u 764 1024 377 88.311 0.605 1.387
-[name] .GPS. 1 u 783 1024 377 73.649 0.766 12.499
#[name] [name] 2 u 652 1024 377 83.509 -0.371 0.725
-[name] .GPS. 1 u 720 1024 377 32.581 1.203 0.082
+[name] .GPS. 1 u 744 1024 377 105.719 0.604 1.952
-[name] .GPS. 1 u 686 1024 377 92.301 3.050 0.447
#[name] [name] 2 u 339 1024 176 0.796 -1.401 0.245
#[name] [name] 2 u 520 1024 376 10.376 -2.257 0.814
[name] 0.0.0.0 16 u - 1024 0 0.000 0.000 4000.00
# time ntpd -gq [above 14 servers/peers with iburst, plus local. No authentication.
Default min/max poll. All appropriate for long-term time
maintenance.]
ntpd: time slew 0.000527s
real 0m45.00s
user 0m0.11s
sys 0m0.55s
[Note that ntpd -gq isn't really done when it unblocks. It has only
initiated a slew. But we'll let that pass becasuse the time is
already way more than "good enough".]
# ntpdate -b [same set of servers and peers, except no local clock. Way
overconfigured for one-time "good enough" acquisition at boot.]
4 Feb 13:21:32 ntpdate[201766]: step time server [IP] offset 0.000647 sec
real 0m6.73s
user 0m0.00s
sys 0m0.00s
________________________________________________________________________
Tom Smith smith at alum.mit.edu,smith at cag.lkg.hp.com
Hewlett-Packard Company Tel: +1 (603) 884-6329
110 Spit Brook Road ZKO1-3/H42 FAX: +1 (603) 884-6484
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