Hi Warren and WAMUG folks.
The short answers to your questions:
1). Your clock didn't change back, because your daylight savings
testing range was too small.
2). IMHO, Apple have decided to keep the naming of time zones simple,
and uncomplicated. Hence, they have chosen to not change the time-
zone name, during DS. (Just my opinion though).
The long answer (to answer 1)...
Firstly to clarify... My previous daylight-savings tests worked fine
for me... The clock automatically dialed back EXACTLY when it
should. I was 100% happy with the results (as posted Feb 21, 2007).
My test workstation was set for the 25th of March 2007, and I watched
the clock automatically roll back. (I started my workstation with the
time of 12.30am. It rolled itself back an hour, one second after the
"second" 2:59.59am, to 2:00.00am. Which is 100% correct.) From my
perspective, the Daylight Savings update is working PERFECTLY, and
has been since I installed it.
Your most recent post suggests that you have also done a test "2
hours" before the daylight savings change over. Your testing methods
may have differed from mine, but these are my conclusions from a
couple of quick tests that I've successfully done with DST:
a). 10 seconds isn't enough time for the computer to register
daylight savings changes. To be exact, 1 hour + few seconds IS
enough... I'll explain this in a moment.
b). It is recommended to have the Date/Time Preference pane 'saved'
and CLOSED during your tests. Otherwise, the computer may think that
you are still adjusting the current time.
c). Run your daylight savings tests WITHOUT a network time server set
on your machine. (Impossible to test with one set really).
d). The LATEST time that you can set your Mac to, to test the
daylight savings update, is 1.59am, on March 25, 2007. Any later than
that, and your computer will decide that your computer is NOT in
daylight savings mode (further explanation below).
My understanding about the daylight savings update is this: it
appears to have a "safety" or "counting" mechanism built into the
system, since the end of daylight savings has two "two o'clocks".
Think about what happens on March 25th... At 2.00am WDST, it's the
first "two o'clock". At 1 second after 2:59.59am WDST, it's now the
second "two o'clock". But how will your Mac know, which 2:00 you're
currently at? The first one? Or the second one?
(We're winding our clocks back, so we get an extra hour, hence we
actually get to re-live the hour of 2am again).
------
To differentiate, there is probably a "counter" programmed into the
updated time system... There will be logic programmed into the
system. Something like:
"If the current date is any date before March 25th, and the time is
before 1:59.59am, then, add one to the counter, to indicate the
presence of daylight savings, since this person is located in Perth,
Western Australia".
OK, your Mac knows it's now in daylight savings time in Perth.
The next major event happens ON the day of the daylight savings
change-over... 1 second after 1:59.59am WDST. The logic will go
something like this:
"Check if in daylight savings mode. Yep, I am (got that "1" in the
DST counter). Check the time... Is it 1 second after 1:59.59am, on
March 25, 2007? Yep. OK. I'm going to add '1' to a new counter called
'first two o'clock'. And I'll let the time tick straight over to
2:00.00am, WDST."
OK, your computer is in the first "two o'clock" hour range. Daylight
savings is 1 hour away from ending. But all is still normal, and
there is no clock-winding yet.
The next event happens at 1 second after 2:59.59am WDST. The logic
will go something like this:
"Check if in daylight savings mode. Yep. Check if one 'two o'clock'
has already passed. Yep. Check time is 2:59.59am on March 25, 2007.
Yep. OK, this is it folks... It's time to leave daylight savings.
Set 'daylight savings finished counter' to '1', and reset the other
counters. Oh, and set the time back an hour, to the 2nd 'two o'clock'.
And that's it. Your computer just wound it's clock back 1 hour, and
is now living in it's 2nd "two o'clock" for the day.
------
So, if you set your computer 2.00am or 2.59am on the 25th of March
2007, you're going to MISS some of those events, and daylight savings
isn't going to tick over.
Instead, try your tests again. In particular double-check:
-Your menu bar clock as the seconds displayed (helps see when the
change-over is going to happen)
-You are in the Perth WA time zone
-You have your network time server setting disabled
-Your time is before 1.59am, March 25, 2007. Any later, and your
tests WILL fail.
-That you have saved and closed the Date/Time system preference.
Using these steps, I've watched daylight savings come and go, and
change successfully again. Today I watched a workstation start at
1.59am, as it ticked over to the first 2.00am, on March 25th. And
then I watched the menu bar clock as it ticked over from 2.59am, out
of daylight savings, into 2.00am (the second two o'clock), WST.
So, this should answer why your computer did not originally change
out of daylight savings mode (when you set it to 2.59am), since your
computer didn't know whether it was in DST or not... It hadn't been
given long enough, to know whether it was meant to change time or not.
Whereas, if the user turns the computers clock to 1.59am March 25,
2007, the computer knows it's still in daylight savings mode, since
there is only one "1.59am" on March 25th. :-)
Hope that answers your questions, and explains the steps I've used to
show that the Apple Daylight Savings update works very well, and in a
predicable manner.
Cheers,
Derek
On 03/03/2007, at 6:03 AM, WAMUG Mailing List wrote:
From: Warren Jones <[EMAIL PROTECTED]>
Subject: Re: Daylight savings testing
Date: Fri, 2 Mar 2007 11:46:14 +0900
X-Mailer: Apple Mail (2.752.2)
I think you've missed my point on this one Shay.
My point was: why didn't my clock roll back the second daylight
saving should have finished (03:00 WDT 25 Mar)? And secondly, why
does my time zone say WST instead of WDT?
Derek said that in his testing it too didn't roll back when it should
but did within an hour.
I repeated my test and left it for quite a while (> 2h) and it still
hadn't rolled back.
I'm aware of what you said about NTP (my sentence actually said the
same thing as you) and I had made a very similar comment on this list
to someone else previously.
cheers
woz
