AIX 6.1 Time Zone and Daylight Saving Time

Time Zone:

http://www-01.ibm.com/support/docview.wss?uid=isg3T1000252

DST problem:

http://www-01.ibm.com/support/docview.wss?uid=isg3T1013017#formatcompare



Summary:

TZ=EST5EDT,M3.2.0/2:00:00,M11.1.0/2:00:00

If you change the System TZ, you need to reboot the machine for activating the change.
If you change the date, you don't need to do rebooting.