US, Canada, Bermuda Daylight Saving Time changes back to Standard Time this fall a week later than in previous years
To handle the US Daylight Saving time change this spring (three weeks earlier this year), you may have applied updates to many of your installed IBM (and non-IBM) HW and SW...and so you may be wondering what additional product updates are required for the fall schedule.
The good news is that the IBM product updates applied in the spring, changed the Daylight Saving Time (DST) schedule for both spring and fall, and for future years (unless the schedule is changed again). If these updates were applied successfully in the spring, no new updates are required for the fall.
There are, however, a couple of areas for caution:
1. Manual intervention is required every year, regardless of the date, for some systems and applications. Some system clocks must be set manually, and many job scheduling applications must be adjusted to handle what might otherwise appear to be a missing hour, or duplicate hour of time as clocks are changed. Operations teams have been managing these activities twice a year for more than 20 years in the US, and this year they need to be handled as usual, but on a different date.
2. At the request of many of our Clients, an option to change the DST rules, without applying maintenance upgrades, was made available in some cases. As always, careful planning is required when applying new maintenance levels over these interim changes. Specifically, the Java Time Zone Utility (JTZU) was provided by IBM as a way to make DST rule updates to Java libraries directly. Many applications imbed Java and Java libraries so this utility was widely used to make the Daylight Saving Time updates with the least system disruption.
2a. If you used the JTZU tool to make the updates for Java related systems and applications, you need to assure that any subsequent maintenance applied to your systems did not overwrite the JTZU update. This can be checked by re-running the JTZU tool, and if out of date DST rules are found, updating the DST rules using the JTZU tool again is recommended. (New Zealand and several other countries have made adjustments to their DST rules since the US changes were included in JTZU and these rules would now be updated as well when a new copy of the JTZU tool is used.)
2b. The JTZU tool will be kept current until further notice with all DST rule changes that occur across the world. Clients who used JTZU should plan to re-run the tool until you are certain that your standard maintenance levels include the DST changes that are important to you, or on an ongoing basis if you have applications and systems that will be affected by DST rule changes around the world.
2c. The latest version of the JTZU tool can be found at the following link: Download latest version of JTZU
Last updated March 10, 2007