Time Change seeting in AIX5.2

[madra]

UK.
This weekend the clocks went back. We changed the time manually on the server about 22:00 on Saturday, to 21:00.

Come Sunday morning the time went back 1 hour again at 02:00

I thought you needed to specify the Time Zone as such:
GMT0BST,M3.5.0/02:00:00,M10.5.0/02:00:00

Whereas on our server it is set to:
GMT0BST


Basically, should the time have changed automatically and if so what prompted it ?


thanks


Madra

 

[KenCunningham]

Possibly the M3.5.0/02:00:00,M10.5.0/02:00:00
is the default if only GMT0BST is specified. Interesting document at:

http://www-1.ibm.com/support/docview.wss?rs=0&uid=isg3T1000252

I don't mind people who aren't what they seem. I just wish they'd make their mind up.

 

[madra]

thanks for your reply

 

[p5wizard]

If your TZ is GMT0BST, then you should not touch your computer's clock, unless to adjust it when it starts to deviate from GMT (or BST) over time - though it's better to use NTP to keep your time setting accurate if you have an NTP server available.

GMT0BST 'knows' how to display the computer's real-time-clock time in 'wall-clock-time'. I.e. it knows that in winter (for UK I believe it is last sunday of october 02:00->01:00 until last sunday of march 02:00->03:00) it should present the time as GMT (no offset) and in summer it should present the time as BST (1 hour ahead of GMT). The real-time-clock inside the computer (CMOS chip) should always stay at GMT!

Some admins prefer to put the whole TZ string
GMT0BST,M3.5.0/02:00:00,M10.5.0/02:00:00 because then you 'see' what is going to happen (and when).

M3.5.0/2:00
M3 = month 3 => march
5 = week 5 => last week
0 = day 0 => sunday
2:00 = 2am
(similar meaning for M10.5.0/2:00)

If I'm not mistaken, TZ can be abbreviated
to GMT0BST,M3.5.0/2,M10.5.0/2
or GMT0BST,M3.5.0,M10.5.0
or GMT0BST

So it means BST starts at 2am on the last sunday of march (becomes 3am) and BST ends at 2am on the last sunday of october at 2am (becomes 1am).

The computer's clock stays at GMT setting, the time is just presented differently in summer/winter.


HTH,

p5wizard

 

[madra]

thanks for the replies. You've confirmed what I thought. Now to explain to the customer !!!

ta

the dog