January 24, 2007

More DST

I made some updates to my wiki page for updating systems to prepare for the DST changes: LINKY
Updates include instructions for Red Hat, Windows and Matlab.


  1. Here is a question - if my machine automatically syncs up to a public NTP time server for my time zone, I should be ok unless the admins of the said server drop the ball, no?

    Same would probably be true for XP desktops - just make sure they get their time from a server that has the correct DST settings and you are good.

    I'm talking about basic desktop machines that are not running any time sensitive applications, servers or etc...

    Or will the internal DST settings mess you up even if you get the time from a remote server?

  2. NTP servers sync your system clock. This clock keeps time in UTC (GMT). The time zone files tell the system what to display the time as for different zones, such as Pacific/Los_Angeles and when to change the zone to DST. I you notice the output from the date command, it will look like this:

    Thu Jan 25 13:37:41 PST 2007

    When DST rolls around, it will look like this:

    Thu Aug 02 13:37:41 PDT 2007

    Notice how the time zone changed from PST to PDT. The magic behind timezones is all done with a change in the zone, not the resetting of the clock.

    For the most part, if you are nor running apps that are time sensitive, you will most likely not be affected. All the underlying technologies (kerberos, LDAP, NTP) all use UTC.

    I would encourage you to patch your systems in the unlikely event you actually bork something.

  3. Ah! Thanks.

    I checked my Ubuntu box and zdump tells me March 11 and Nov 4 so I'm all set.

    Any idea if the Windows hotfix will be pushed out as an automatic update anytime soon?

    Sigh... I'm going to pencil in an update of PHP and MySQL on my work servers for some time in Feb...

    My POS JDS system doesn't even have zdump installed... I'm not even gonna bother with that thing. I'm istalling Solaris 10 on it. :P