[Info-vax] Time change

[Michael Moroney]

JF Mezei <jfmezei.spamnot at vaxination.ca> writes:

>How is this implemented in alpha ? Does the system do a glorified
>SYS$SETTIM to call a routine to execute at the next scheduled time
>change ?  or is there some other type of mechanism that allows VMS to
>schedule some event in the long term ?

>Also, if I have an alpha that was shutdown during this time, when it
>next boots, will it automatically change its time ?

I had to deal with this during the last time change, to try to prevent
the setback from happening automatically with software that really 
couldn't deal with it.

(the following is true only if SYSGEN AUTO_DLIGHT_SAV is set to 1, and
things like NTP time synch aren't enabled. What's the setting on your
VAX?)

The JOB_CONTROL process has a $SETIMR scheduled to expire at the time of
the time change, and when it does, JOB_CONTROL sets the time according to
the time zone rules.  It reads the info in when it starts up, and it has
enough smarts to set the time right then if the time change happened when
the system was down.

$ ANALYZE/SYSTEM
SDA> SET PROCESS/IND=E   !JOB_CONTROL
SDA> SHOW TQE
Timer queue entries
-------------------

  TQE                                                             PID/
address                 Expiration Time                 Type    routine
--------   -----------------------------------------   ------   --------
...
880EA380   00A93E1F.7B714530  1-NOV-2009 02:00:00.00   TSA---   0001000E   JOB_CONTROL
SDA>

Next time change will take place Nov 1 at 2:00 AM.



You may notice that $SETIMR can schedule events to happen thousands of
years in the future, if you can manage to keep your system up that long.

Aside: Were you guys in Canada supposed to change your time this last
weekend?  The date of the time change was recently changed.