Unix Tip: Wake up and patch the OSes

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Time is running out for anyone planning to ready their systems for the biggest time-related change since Y2K -- the 2007 Daylight Savings Time change. As Americans turn their clocks ahead one hour this year -- three weeks earlier than previously, systems administrators will be well advised to ensure their systems will do the same. Timezone configurations on systems from Solaris and Linux to Windows will require updates if not already updated through a patch, OS upgrade or service pack, to accommodate the new dates for switching to and then back off daylight savings.



No one is completely sure how all of our computer applications and business processes will be affected if systems aren't patched or if only some of our systems are patched while others are left with the old timetables for switching from standard time to daylight savings. The ill effects are most likely to be felt when systems which have not been patched share processes or databases with systems that have not been patched, creating time differences that could wreak havoc on any form of processing in which the timing of events is critical.



The reason for this change derives from daylight savings changes incorporated into the Energy Policy Act of 2005. One provision of this act specifies that US clocks -- for the first time this year -- will be moved ahead on the second Sunday in March instead of the first Sunday in April. In 2007, that's March 11th instead of April 1st. In addition, the change back to standard time will occur one week later -- the first Sunday on November instead of the last Sunday in October. The purpose of this change is not to avoid having all of America messing with our clocks on April Fools' Day, but to conserve energy by increasing the period in which daylight savings time is observed. As a result of these changes, daylight savings will last four weeks longer starting this year. This provision amends the Uniform Time Act of 1966 -- the act that regularized the observance of daylight savings time in the US. Prior to the 1966 act, many states observed daylight savings time, but only in accordance with local customs.



Not just for the US



Daylight savings times patches are not just for those of us who live in the US. Many countries around the world have been implementing changes to their daylight savings time start and end dates. The latest updates to the timezone files, available as patches from all of the major system vendors, will accommodate most if not all of these changes. On Solaris systems, most of these changes are effected through the timezone files in the /usr/share/lib/zoneinfo directories. POSIX timezone changes, on the other hand, require updates to libc files.

If you are running Solaris 10, you probably already have some version of the timezone patch installed. You can verify this with the showrev command shown below:

# showrev -p | grep 122032
Patch: 122032-02 Obsoletes:  Requires:  Incompatibles:  Packages: SUNWcsu

122032 is the Sparc version of the patch for Solaris 10. As of this writing, the current version is 122032-03. Check SunSolve online to determine which patches your Solaris systems will need.

You may not need the latest version of the timezone patch. Later versions of the patch will include timezones for many additional countries (nearly 200 in 122032-03 and the corresponding patches for other Solaris releases. Regardless of where you are located, however, some version of the DST patch is probably required.

Don't wait until Friday, March 9th, to begin your patching. The patch doesn't take long to install (it took me about 1 minute and 15 seconds on one of my Solaris 10 systems), but the patch should be installed in single user mode and the system should be rebooted afterwards. Upgrading early will certainly not cause any problems. Patched systems will simply continue running with their current clock times until March 11th.

The libc patch may be required and, if so, will take longer to install, depending on the packages installed on your system.

Time zone patches for many systems, not just Solaris, are available via this web URL: http://www.dstpatch.com/

Installing a DST patch is a simple operation, but requires the use of single-user mode and a system reboot. Follow these steps to install 122032-03:

init 1 -- takes you to single user mode
cd to the directory in which the patch file is located
unzip 122032-03.zip
patchadd 122032-03
reboot

Determining what patches you will need and making plans for updating your systems may take as much time as patching the systems, so this is a good time to get started if you haven't already. March 11th is not all that far off and, well, you don't want to feel foolish on April 1st.