Australian DST Change for 2006 for AIX

For systems using the Time Zone (TZ) variable to adjust for Daylight Savings Time (DST), a manual adjustment may be needed to cover the changes made by Australian Governments to Australian DST in 2006 to take account of the Commonwealth Games. You should check whether your system is utilizing Daylight Savings Time (DST) and how this will affect your systems and applications. If you do change the Time Zone (TZ) variable any changes made to the time zone will NOT fully take effect until the next system boot.

Useful Information

Review the Technote, "Managing the Time Zone Variable" which discusses the implications of making changes. You can find this Technote at:

http://www14.software.ibm.com/webapp/set2/srchBroker/views/srchBroker.jsp
Enter title in "Search AIX operating systems".
Select "Technote" at the bottom of page.
Select "Go".

Before the current timezone change date, the TZ variable needs to be changed as follows, a reboot is recommended to fully implement the change:

ACT. NSW. VIC.
TZ=AEST-10AEDT,M10.5.0/02:00,M4.1.0/03:00
Tasmania
TZ=TASST-10TASDT,M10.1.0/02:00,M4.1.0/03:00
S.A.
TZ=ACST-9:30ACDT,M10.5.0/02:00,M4.1.0/03:00

After the 2nd of April 2006, the TZ variable needs to be reset to the states normal TZ as below, a reboot is recommended to fully implement the change.

Example is based on current rules at time of creation. Customers should contact their local Government office to verify the start and stop rules for DST in their locality:

NORMAL Daylight Savings Time Zone variables for AIX in Australia and New Zealand

Examples based on rules current at time of creation. Customers should contact their local Government office to verify the start and stop rules for DST in their locality:

New Zealand (AIX adjusted) http://www.dia.govt.nz/
TZ=NZST-12NZDT,M10.1.0/02:00,M3.3.0/03:00
=CUT -12 DST from from First(1) Sunday(0) in October(10) 2am(02), until the Third(3) Sunday(0) in March(03) 3am(03)
Queensland (AIX) http://www.qld.gov.au
TZ=EET-10
=CUT -10 No Daylight Savings
N.S.W. VIC A.C.T. (AIX adjusted) http://www.nsw.gov.au http://www.vic.gov.au http://www.act.gov.au
TZ=EET-10EETDT,M10.5.0/02:00,M3.5.0/03:00
=CUT -10 DST from the Last(5) Sunday(0) in October(10) 2am(02), until the Last(5) Sunday(0) in March(03) 3am(03)
Tasmania (AIX adjusted) http://www.tas.gov.au
TZ=TASST-10TASDT,M10.1.0/02:00,M3.5.0/03:00
=CUT -10 DST from the First(1) Sunday(0) in October(10) 2am(02), until the Last(5) Sunday(0) in March(03) 3am(03)
N.T. (Custom) http://www.nt.gov.au
TZ=ACST-9:30
=CUT -9:30 No Daylight Savings
S.A. (Custom) http://www.sa.gov.au
TZ=ACST-9:30ACDT,M10.5.0/02:00,M3.5.0/03:00
=CUT -9:30 DST from the Last(5) Sunday(0) in October(10) 2am(02), until the Last(5) Sunday(0) in March(03) 3am(03)
W.A. (AIX) http://www.wa.gov.au
TZ=WAUST-8
=CUT -8 No daylight savings

Example

For ACT, NSW, and VIC the TZ environment variable needs to change from:

TZ=EET-10EETDT,M10.5.0,M3.5.0/03
TO
TZ=EET-10EETDT,M10.5.0,M4.1.0/03

This change can be made with the chtz command, through smit 'smit chtz' or by editing the /etc/environment file.

 
   1. smitty chtz
         1. Answer "1 yes" to "Use Daylight Savings Time?"
         2. Select your TZ variable
                 Example: (EET-10EETDT) Eastern Australia (CUT+10)

                                Change Time Zone
   Type or select values in entry fields.
   Press Enter AFTER making all desired changes.
  
                                                        [Entry Fields]
   Time zone                                           EET-10EETDT
   Day Light Savings Time Offset from CUT([+|-]HH:MM: []
   SS)
   Start Daylight Savings Day([Mmm.ww.dd|Jn])         [M10.5.0]
   Start Daylight Savings Time(HH:MM:SS)              []
   Stop Daylight Savings Day([Mmm.ww.dd|Jn])          [M3.5.0]
   Stop Daylight Savings Time(HH:MM:SS)               []
  
     ---- change for the  "Stop Daylight Savings Day([Mmm.ww.dd|Jn])" 
         from "M3.5.0" to "M4.1.0", for the impacted areas and 
         "Stop Daylight Savings Time(HH:MM:SS)" to 03:00:00"

Notes

In 2006, all Australian states with DST are changing the rules for the Commonwealth Games. DST ends on April 2nd in ACT. NSW. VIC. SA. and TAS ie 1st Sunday in April.

In 2000, some Australian states changed their DST rules for the Olympic Games.

By default, if the change time is not specified in the TZ variable, AIX uses 2am local time. In Australia, the daylight savings changes are stipulated to occur at 2am standard time. So, moving into daylight savings, the time moves from 2am to 3am local time, and moving out of daylight savings, the time goes from 3am to 2am local time.

After making this change kill/stop/restart " cron ", so that it will pick up the new TZ when it is automatically restarted by init.

Other applications that rely on TZ would also need to be restarted or users should log out and back in to pick up the change.

A reboot, while probably not essential, would ensure that all processes pickup the change. If a reboot does not occur, then every process which was running prior to the change will continue to use the older value.

For further information or if you have any problems utilizing this information, feel free to log a software support call.

Other platforms

Australian DST Change for 2006 for HMC
Australian DST Change for 2006 for Linux on POWER
Search IBM.com Commonwealth Games DST