[ntp:hackers] Re: NTP and leap-seconds

todd glassey todd.glassey at worldnet.att.net
Wed Jul 5 00:58:00 UTC 2006


Notice that this makes the Operator the accountable evidence as to the
systems being operated in a  timely manner... Not kosher in anyone's book.

Todd

----- Original Message ----- 
From: "David L. Mills" <mills at udel.edu>
Cc: <hackers at ntp.org>
Sent: Tuesday, July 04, 2006 5:38 PM
Subject: Re: [ntp:hackers] Re: NTP and leap-seconds


> Tim,
>
> Very tiny amendments. First, IBM Sysplex 9037 is listed at $100,000.
> Second, it does the leap, but the operator has to tell it when
> beforehand. IBM's suggestion for operators that really want local time
> is to turn the machine off during the Fall leap backward interval. In a
> global system, that would mean dark computing for one day.
>
> Dave
>
> Tim Shoppa wrote:
>
> > "todd glassey" <todd.glassey at worldnet.att.net> wrote:
> >
> >> I have suggested that NIST and USNO and the other National Timing
> >> Laboratories submit secured notice - through signed emails, to the
> >> Satellite
> >> Timelords of the Non-Federally Operated leaves of the global NTP
> >> Services.
> >>
> >> I am a Professional Auditor, and as such assure you folks that the US
> >> Government already uses the exact same thing for Notices of
> >> Electronic Court
> >> Activities... So it does work.There is an entire practice model which
if
> >> this group is interested, I can submit later this week.
> >
> >
> > All of this seems like extreme overkill considering that few of the
> > OS's that underly NTP, and very few syscalls/libraries/applications,
> > support the concept of leap seconds in a Good Way. Usually
> > we just want to supply non-leapsecond aware applications
> > with a monotonically increasing time that isn't off by more than
> > a second or so in a leapsecond event.
> >
> > There are a very few OS's that do support TAI-like timescales (e.g.
> > a base clock that always ticks forward one second every second no matter
> > what) and use OS-supplied tables to do leapsecond and
> > timezone/calendar magic.
> > But as far as I know none of them use NTP nor do they support automagic
> > net propogation of leapsecond/timezone tables. An example is z/OS.
> > I could be wrong and maybe parallel sysplex operation now allows NTP
> > supplied
> > time; I am not a Mainframe Guru although I do bump my horns up against
> > their horns at meetings :-) Last time I checked a refclock for a
> > parallel sysplex rang in in the $30000-$60000 price tag.
> >
> > Of course a similar tick-forward-a-second-every-second-no-matter-what
> > timescale is the GPS timescale. And even there, there are a lot of
> > embedded timing devices that do NOT properly interpret the leapsecond
> > corrections distributed (e.g. Z3801A's) in all circumstances and
> > we end up with NTP drivers for those GPS refclocks that apply their
> > own correction to the leapsecond-pending flag correction!
> >
> > Tim.
>
>
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