Red Hat Knowledgebase

In the calendar year 2006 and 2007, a number of countries have altered the dates on which they observe Daylight Savings Time (DST). The earliest of these changes will occur on March 26, 2006 for those observing Australian DST and in certain parts of the state of Indiana (USA). (Reference: http://aa.usno.navy.mil/faq/docs/daylight_time.html)

The key points being:

1. Australia delaying the end of DST by one week for 2006 only to support the Commonwealth games. Instead of ending at 3am on March 25, 2006 it will end at 3am April 2, 2006.
2. The U.S. Energy Policy Act of 2005 implements change for the US. Starting in March 2007, DST in the United States will begin on the second Sunday in March and end on the first Sunday in November.
3. Canadian Provinces Quebec(QC), Ontario(ON), Nova Scotia(NS), Nunavut(NU), Saskatchewan(SK), Manitoba(MB), New Brunswick(NB), Prince Edward Island(PE), Alberta(AB), British Columbia(BC), Newfoundland and Labrador(NL), Northwest Territories (NT) and Yukon(YK) will follow US DST changes which will come into force in March 2007.
4. Western Australia has introduced a three year trial of DST which has already started on Dec 3rd 2006 and ends on last Sunday in March. A separate article dealing with this change can be found here: http://kbase.redhat.com/faq/FAQ_61_9647.shtm
5. The Bahamas will also follow US DST changes which will come into force in March 2007.

Packages have been released for all three releases of Red Hat Enterprise Linux, and there are a few points in the update that users should be aware of.

Resolution:

Update the tzdata packages atleast to the following level:

	tzdata-2005m-1.EL4

This was the initial push of this change in tzdata. This includes changes for the US.

If the system is registered with Red Hat Network (RHN), use the below command to install the latest tzdata packages:

# up2date -u tzdata

A caveat of only updating tzdata is there, but there is no built-in mechanism to update /etc/localtime to the latest timezone unless the system is already running glibc-common version 2.3.4-2.20 or greater. If the system is not on these versions, there are additional options. Any of these can be used to update the localtime information:

• Update both glibc-common and tzdata at the same time in the same up2date run or with the rpm command. This will lay down a new binary from glibc-common called tzdata-update which resides in /usr/sbin. The tzdata package is a requirement of glibc-common, so it will be installed first and will lay down the new tzdata files, then when glibc-common reaches the %post section this is reached:

  	%triggerin common -p /usr/sbin/tzdata-update -- tzdata
  

  This will update /etc/localtime accordingly.

• Update /etc/localtime by hand after installing the latest tzdata package. This can be done with a simple copy command:

  	cp /usr/share/zoneinfo/$CURRENT_TIMEZONE /etc/localtime
  

  where $CURRENT_TIMEZONE is the local timezone (e.g. America/NewYork).

• Simply re-run system-config-date, and save the settings. This will copy over the updated timezone file to /etc/localtime. This is the easiest method, but is troublesome if no X Windows server is running.

Once updated, any application relying on /etc/localtime will need to be restarted. The easiest solution would be to reboot the system to ensure that all applications have been updated.

zdump -v /etc/localtime |grep 2007

Reference:
http://rhn.redhat.com/errata/RHEA-2005-656.html