How to update IBM i for the new Daylight Savings Time (DST) rules


This article is now available in our new knowledge base: How to update IBM i for the new Daylight Savings Time (DST) rules


In 2007, Daylight Savings Time was expanded to a wider range of dates in the US.  PHP scripts may display the wrong time if the new timezone descriptions have not been loaded on the IBM i.  This article explains how to find the IBM instructions to update IBM i for the current DST start and end dates.


IBM i, any currently supported version.


Please update your system with the new DST timezone descriptions. For V5R4 or V5R3, you will need to verify that you have the required PTF.  You will find the information you need here:

Daylight saving time (DST) Information

You can also update your system immediately. On the above listed page, click the link labeled "Daylight Saving Time Manual Instructions".

On the page that comes up, find "Operating System Daylight Saving Time Manual Instructions" and expand the topic by clicking the blue arrow. Then, find your time zone on the list, and expand that topic. Follow the instructions for your time zone.

For newer versions of IBM i, you just need to make sure you have the correct value specified for the QTIMZON system value.  This table, from the article linked to above, tells the correct values.

Time zone description New 2007 rules
Prior  QTIMZON value
Atlantic Time QN0400AST2 QN0400AST
Eastern Time QN0500EST3 QN0500EST
Central Time QN0600CST2 QN0600CST
Mountain Time QN0700MST3 QN0700MST
Pacific Time QN0800PST2 QN0800PST
Alaska Time QN0900AST2 QN0900AST
Hawaii-Aleutian Time QN1000HAS2 QN1000HAST