Paul Gilmartin wrote:
>Leap seconds are a different issue. z/OS shuts down all applications
>during a leap second. Google and Amazon both steer their clocks
>slow (less than 0.01 percent) for several hours centered on a leap
>second.

No, you're not fully characterizing z/OS's capabilities here. You're
drawing a false dichotomy.

A leap second "spin" is one *option* customers have. It's not a
requirement. The other option available is ... gradual steerage to adjust
for the leap second! It takes approximately 7 hours for the IBM z System
and z/OS to smooth out one leap second. Refer to IBM Tech Doc # WP102081
for more information:

https://www.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP102081

So, unlike Google and Amazon, *you* choose. If you want precise timing at
every moment, choose that option (not available with Google and Amazon). If
you want gradual steerage, choose that. Unlike Google and Amazon, IBM does
not force one choice on its customers here. And you can change your mind
before the next leap second if you wish.

Come to think of it, there's probably a third option: do whatever you want
on your external time reference, then just let Server Time Protocol and
z/OS steer from that reference as they always do. Specifically, if you
think ~7 hours is too fast a pace, and if your time reference can be
configured to steer substantially more slowly across the leap second
(sounds like a reasonable option for such things), all that should work. I
don't see why it wouldn't, anyway.

--------------------------------------------------------------------------------------------------------
Timothy Sipples
IT Architect Executive, Industry Solutions, IBM z Systems, AP/GCG/MEA
E-Mail: [email protected]

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