Possibly Historical Document - Last Updated Wed Oct 3 12:20:34 2007

Using Javascript to check DST settings on your computer (the one your browser is running on)...

The current time is

Browser statistics from script above 8 March 2007 - 11 March 2007, since 11 March 2007

Checking DST settings in Java... if you don't have it installed, ignore this box.

If your DST settings are correct, you need do nothing. Unless you use calendar features in older versions of Outlook (pre-2007), or similar software, in which case read on.
If your PC clock is incorrect, check your NTP settings.

2007 Daylight Savings Time changes - Y2K revisted

(the reason Y2K was such a non-event was the millions of hours put in to remediating it by IT staff and engineers. Were it not for their efforts, we may not have had planes falling from the sky, but we for sure would have had chaos at the terminals)

Specifc details on this page may refer to Vancouver, Canada (Pacific Timezone), but DST changes affect most of the US and Canada.

In March 2006 the BC government decided to follow the US and change when daylight savings time starts and ends (but it still won't match Europe). So PDT will start on March 11 this year, and end on November 4. See here for maps of Canadian timezones.

Most computer systems, and a number of other devices such as PDAs, Webcams, VCRs etc. use Universal Time internally and work out local time using a list of rules. Unless the rules are updated, the computer clocks will be an hour wrong for most of March and around the end of October. This may cause problems ranging from email apparently arriving before it was sent, to missed appointments or missed flights. (I for one always set my watch from my computer, since NTP keeps it accurate to a fraction of a second).

Updating systems: - information for: Windows XP, Windows NT, 9x, Linux, Java, MacOS, Solaris, Other

Linux

Recent Linux systems should be automatically updated; check using date -d as below. You can also list the rules for your zone (or any arbitrary zone) with zdump. Note that the calendar and date commands are retroactively correct, at least back to 1918 or so).

If DST is not correct, try to update the zone data with yum. Older systems (which may include time data in the glibc package) require the timezone source to be recompiled with zic, unless you want to recompile the entire glibc.
Mandriva timezone data is in the "timezone" RPM; RedHat/Fedora is in "tzdata". 

$ date -d '15 march 2007 UTC'   - expect "Wed Mar 14 17:00:00 PDT 2007"

$ /usr/sbin/zdump -v /etc/localtime |grep PDT|grep 2007
America/Vancouver  Sun Apr  1 10:00:00 2007 UTC = Sun Apr  1 03:00:00 2007 PDT isdst=1 gmtoff=-25200
America/Vancouver  Sun Oct 28 08:59:59 2007 UTC = Sun Oct 28 01:59:59 2007 PDT isdst=1 gmtoff=-25200

(these are the old dates)

# yum update tzdata
# cp /usr/share/zoneinfo/America/Vancouver /etc/localtime
or 
$ wget http://andrew.triumf.ca/northamerica.rules.txt   (link)
# /usr/sbin/zic northamerica.rules.txt
# cp /usr/share/zoneinfo/America/Vancouver /etc/localtime

$ /usr/sbin/zdump -v /etc/localtime |grep PDT|grep 2007
America/Vancouver  Sun Mar 11 10:00:00 2007 UTC = Sun Mar 11 03:00:00 2007 PDT isdst=1 gmtoff=-25200
America/Vancouver  Sun Nov  4 08:59:59 2007 UTC = Sun Nov  4 01:59:59 2007 PDT isdst=1 gmtoff=-25200
(these are the new dates)

Note that in some distributions /etc/localtime is a symlink to the current zone. In RedHat-derived ones, it is not (so you have to copy the zone, as above). My computers use RedHat/Fedora, so that is what I've tested.
Note that other jurisdictions apart from North America have updated DST rules, so to do it properly you should compile all the zone files, not just northamerica.rules
Note you have to re-start your browser (in general, any program that uses timezones) for the changes to take effect.

Note you may have to restart services such as MySQL, since they read timezone information only at startup. This may include syslogd, sendmail, httpd ...
12 March: httpd appears to handle it. syslog appears to handle it also. Sendmail requires a reload.
14 March: so does sshd, apparently

See also FAQ_80_7909 in the RedHat Knowledge Base

Java

Sun Java has its own timezone info. It's best to update the whole Java package; there have been some security issues, too. (the Sun JRE is usually in /usr/java on Linux)

Here's an applet that figures out if JRE has been updated: Jtime.html (includes links to Sun Java download and update tool)

Windows 2003, XP, Vista

TRIUMF users see desktop support - patches are applied automatically for PCs that are in the TRWIN domain.

Non-TRIUMF users see Daylight Saving Time Help and Support Center. Newer Microsoft systems should have been patched automatically.
Users can download updates manually from Microsoft Knowledge Base 928388.

To check if a system is updated, run the "adjust date/time" applet (right-click the time on the toolbar, as an administrator). Set the date to March 15th and click "Apply". The timezone should show Pacific Daylight Time. Restore the current date and click "OK".

Windows NT, 9x

NT and earlier are no longer supported by Microsoft so users will have to patch manually; see Preparing for daylight saving time changes in 2007

You may run TZEDIT.EXE to edit individual timezone entries, or you may install this file with REGEDIT:

- save and double-click - to update the registry entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones (or Microsoft\Windows\CurrentVersion...) as per Microsoft Knowledge Base 914387
Note that you need to tell Windows to use the new timezone rules; in Control Panel/ Date & Time select Timezone and click OK. You will also need to re-start your browser (or other programs) for the change to take effect.
From a correspondant: 
1. Click Start, then Run, and enter the following command to bring up
the date/time applet (or simply double-click the clock icon on the
Windows toolbar)
   control timedate.cpl,,/Z

2. Click the Time Zone tab, click to select the "(GMT-08:00 Pacific Time
(US & Canada)" time zone from the dropdown menu, and then click Apply.

Note that other Windows applications, in particular calendaring programs such as Outlook 2003 or earlier versions, require updating. See e.g. Preparing other Microsoft software products for the 2007 DST changes

Other Systems

UBC has some information on other systems (MacOS, Cisco, PDAs)

So does ITworld Canada

A.Daviel