Subject: Re: dom0 and timed
To: Daniel Hagerty <hag@linnaean.org>
From: Sarton O'Brien <bsd-xen@roguewrt.org>
List: port-xen
Date: 02/06/2008 12:04:25
Daniel Hagerty wrote:
> > Forgive me but does this relate more to the actual time keeping? The
> > main problem I saw was that at some point, ntpd would stop servicing
> > clients and would require a restart. I have a feeling it related to the
>
> The PLL issue is addressed at "ntp is causing kernel panics".
Oh, sorry, I didn't link the two. I'll disable the kernel option.
> > addition and removal of vifs within a dom0. In the end, that may just be
>
> Very likely. I don't know what NTP's current story is for dealing
> with this better, but historically ntp has done strange things in the
> face of interfaces coming and going. The -I option might help, but
> probably not. I'd like to think they have a story for this common
> problem, but I don't know what it is.
>
> This particular failure mode of the udel ntpd has long been a
> favorite advertising point for openbsd's ntp implementation.
> Personally, if I couldn't get udel ntp working in a situation, I'd try
> openbsd's ntp before going with timed.
I seem to remember trying -I in the past with little success but I'll
double check.
> Timed's biggest single issue is that it merely aims to keep clocks
> synchronized. This is a very different goal from ensuring that clocks
> have the correct time, and tick one second per second.
So ntpd is a time keeper/monitor and timed is a clock synchroniser ...
gotchya.
> NTP will certainly beat timed in accuracy or whatnot, but really
> the big difference that any normal person will care about is correct
> time vs synchronized time.
>
>
> Anyway, I only say anything because you said "timed" and also
> something about "timed and ntp", where the latter is certainly a
> "don't do that". Pick one.
OK, I understand now ... so assuming timed is still relevant ...
wouldn't you need a master time source using ntpd to synchronise time
with and wouldn't that source require a master timed service so that
clients can synchronise an accurate time?
There seems to be a bit of a 'gothcya' when it comes to picking one :S
Thanks again,
Sarton