Re: Time change this weekend

DST observance by way of time zones (time jumps) and system clock adjustment
(clock slowdown/speedup) were both introduced in V5R3 and have worked in the
same fashion from day one.

What you propose (using clock adjustments) is possible but a real pain. A
few people, including yourself evidently, did take this approach "way back
when" but you are effectively telling falsehoods to the system -- something
that all too often comes back to bite you (much like using CCSID 65535 to
support multiple encodings) down the road.

Bruce Vining

On Sat, Oct 31, 2009 at 1:53 PM, Justin C. Haase <jchaase@xxxxxxxxx> wrote:

Now you're going to make me go try it on one of my test systems - I can't
even remember all the stuff I did to get it to work! But it did work.
Maybe I had to change the offset and then cycle NTP - was for a spring
ahead
in 2005. Or maybe it was automatic in the first iteration of early POWER5
and IBM took away the feature with the PTFs that added the DST date
changes. Only did it once - apparently something has purged that memory
from my brain.

Not going to lose too much sleep over it, but I'll see if I can recreate.
Net of this whole thread: as long as your zone is right, the system pops
back (or forward) and everything usually makes it through OK (unless you
haven't patched your MQ Series).

On Sat, Oct 31, 2009 at 1:47 PM, Justin C. Haase <jchaase@xxxxxxxxx>
wrote:

Just saying that a slide of time using NTP (vs. a snap with the time zone
settings) is possible - I've done it before, took a lot of messing around

to

get it to work. Wouldn't recommend it, aside from all the fiddling with
settings - mainly because if you have a transaction that happens during

that

hour, what time did it REALLY occur?


On Sat, Oct 31, 2009 at 1:35 PM, Lukas Beeler <
lukas.beeler@xxxxxxxxxxxxxxxx> wrote:

On Sat, Oct 31, 2009 at 19:32, Justin C. Haase <jchaase@xxxxxxxxx>

wrote:

You can make the system clock "crawl" or "race" if you use NTP client

and

set NTP to have a larger "adjust time" than 60 minutes and use a time

zone

that doesn't have an automatic DST change (and ensure your time source
changes). By default I believe it's 20 minutes +/-, so this won't

work

without some manual intervention. Otherwise the system just snaps to

the

new hour and continues on its way.

NTP always uses UTC, so i can't see how this should have any effect on
DST changes.

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