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

Brad Knowles brad at stop.mail-abuse.org
Sun Feb 6 18:58:59 UTC 2005

At 11:51 AM +0000 2005-02-06, Tom Smith wrote:

>  Maybe you missed the data showing identical conditions and
>  a greater than 50:1 difference between the 2? One is 2 notes back.
>  The note you replied to. There are 2 or 3 other previous posts with
>  detailed data showing the same ting.

	Those could be reasonably explained by DNS caching effects.  When 
comparing the performance of ntpdate to ntpd, you need to compensate 
for that.

>  Including a down server. ntpd has the same problems if you don't
>  give it enough servers if they're down, after all.

	Right, but if you feed ntpdate only one server, or only three 
servers (as cut down from your "large" ntp.conf), in order to try to 
get it to start up that vitally critical few seconds faster, and that 
server is down (or one or more of those servers is down), you could 
well be seriously toasted.

	This is a case which ntpd handles better than ntpdate, given 
suitably large numbers of servers to each.

>  Yes, welll, perhaps. I'll take the demonstrated and often seen failure
>  modes of not doing it over the theoretical ones, though.

	There's a limit to what we can do when comparing the 
dain-bramaged use of simple tools which people have in the past shot 
themselves in the foot.  The best we can do is to try to improve the 
tools in the future, so as to try to make it more difficult for 
people to shoot themselves in the foot.

	The problem is that while we're trying to improve the overall 
performance of the tools as-used in the field (and help protect 
people from their own stupidity), you're asking us to give you more 
thermonuclear foot-shooting leeway, because you believe that you know 
how better to deal with this problem than Dr. Mills.

	I am not convinced that these are design goals that can be made 
to be compatible.

Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.

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