Re: REMINDER: LEAP SECOND

[Harlan Stenn <stenn () ntp org>]

Doug Barton writes:
> This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
> On 6/19/15 2:58 PM, Harlan Stenn wrote:
> > Bad idea.
> >
> > When restarting ntpd your clocks will likely be off by a second,
> > which will cause a backward step, which will force the problem you
> > claim to be avoiding.
> >
> > There are plenty of ways to solve this problem, and you just get to
> > choose what you want to risk/pay.
>
> You misunderstand the problem. :) The problem is not "clock skips
> backward one second," because most of the time that's not what
> happens.  The problem is that most software does not handle it well
> when the clock ticks ... :59 :60 :00 instead of ticking directly from
> :59 to :00.

POSIX NEVER shows :60.

> THAT problem is avoided by temporarily turning off NTP and then
> turning it back on again when "the coast is clear." Most software can
> handle the "clock skips forward or backwards one second" problem
> fairly robustly,= and as Baldur pointed out by doing the reset in a
> controlled manner you greatly reduce your overall risk.

Time going backwards is deadly to a number of applications.

But apparently not to applications you care about.

You're also not doing anything where somebody is going to get sued
because a timestamp is off by a second.  There are people for whom this
is a very real risk.

H