Over the past few weeks I have gotten asked several times about what we are doing at St. Mark’s about the date changes for the start and end of Daylight Savings Time (DST). The US Congress passed the Energy Policy Act in August 2005 that moves the start of DST three weeks earlier and the end one week later.

We looked at every component, operating system and application for possible issues with the Daylight Savings Time change. Of course, some are more critical than others.

We started with Windows/Exchange/Good Mobile Messaging knowing that they would be affected most by the changes. Microsoft recommends the following order for applying patches:

Normal guidance
  1. Apply updates to Windows operating systems on Windows Servers.
  2. Apply updates to Windows operating systems on individual workstations.
  3. Apply the Exchange Server DST update.
  4. Run the Exchange Calendar Update tool against all affected users, servers, or both OR correct individual e-mail application calendars using the Outlook Time Zone Data Update tool.

(Note that Microsoft has different guidance for organization that rely heavily on Outlook Web Access.)

For the first step we manually patched our Windows 2003 servers, this went smoothly for us.
We used WSUS to push out the operating system patches to our Windows XP desktops.
After step 3 we had to update Good Messaging Server to 4.9.3. Then we ran the Exchange Calendar Update tool. We didn’t have to immediately update our Palm OS Treos because we have them set to use network time and we don’t use any of the native applications. We probably will get to updating them later on.

As for our Linux boxes, all of them are running Centos 4.4 and are patched (via yum) with the latest tzdata packages, they also are set to use NTP. NTP is running on our Asterisk box, and relies only on Greenwich Mean Time (GMT) – DST information is handled by the operating system.

We then looked at the various applications we have running and found that all of our applications rely on the operating system for time and date, so no patching was necessary. I would still check on each application and verify that it isn’t affected. Note: Some applications running Java Development Kits or Virtual Machines may need to be updated.

For our Linksys IP SPA-941 and SPA-922 phones we have to update the DST string to:
start=3/8/7/2:0:0;end=11/1/7/2:0:0;save=1

Our surveillance camera vendor, Envysion released a patch for their DVR software, instructions are here.

Our Cisco network infrastructure is all configured to use NTP, so it should be fine but we are looking at the patches.

Others on DST updates:
Jason Powell – 2007 Daylight Savings Time Changes This Year
Tony Dye – DST Update Woes
Techsoup Discussion on DST
Technorati Search: Daylight Savings Time

Microsoft
Cisco

Update: Geeks Are Sexy points to a great site (DSTPatch.com) for addressing DST issues.