HP OpenVMS System Manager's Manual, Volume 1:...

Setting System Time

Setting Time in an OpenVMS Cluster Environment

Setting Time Using the Battery-Backed Watch (BBW) (Alpha Only)

Adjusting for Daylight Saving Time  

• Whether DTSS is in use



• The version of OpenVMS



• The architecture (VAX or Alpha)



• System parameter AUTO_DLIGHT_SAV (OpenVMS Alpha Version 7.3 only)

If you are using the Distributed Time Synchronization Service (DTSS), DTSS makes the necessary changes between daylight saving time and standard time. See Distributed Time Synchronization Service (DTSS).

OpenVMS Version	Architecture	AUTO_DLIGHT_SAV	See
7.3	Alpha	1	Automatically Adjusting for Daylight Saving Time (OpenVMS Alpha Version 7.3 Only)
7.3	Alpha	0	Manually Adjusting for Daylight Saving Time on OpenVMS Version 7.3
7.3	VAX	n/a	Manually Adjusting for Daylight Saving Time on OpenVMS Version 7.3
7.2 and earlier	VAX or Alpha	n/a	Adjusting for Daylight Saving Time on OpenVMS Version 7.2

Automatically Adjusting for Daylight Saving Time (OpenVMS Alpha Version 7.3 Only)  

OpenVMS Alpha Version 7.3 and later contain a system parameter, AUTO_DLIGHT_SAV, that controls automatic switching between standard time and daylight saving time.

If AUTO_DLIGHT_SAV is set to 1, an OpenVMS Alpha Version 7.3 (and later) system automatically sets the time forward or back when local time changes between daylight saving time and standard time.

If AUTO_DLIGHT_SAV is set to 0 (the default), OpenVMS does not automatically change between daylight saving time and standard time.

The AUTO_DLIGHT_SAV parameter and the automatic changes between daylight saving time and standard time are implemented only on OpenVMS Alpha Version 7.3 and later.

For this to work correctly, you must set a time zone rule for your time zone. See Setting Time Zone Information on OpenVMS Alpha Version 7.3 and Later for information about setting time zone rules on OpenVMS Alpha Version 7.3 systems.

To enable or disable the automatic changing from standard time to daylight saving time, you must modify AUTO_DLIGHT_SAV. The modification will not take effect until you reboot the system. See HP OpenVMS System Manager's Manual, Volume 2: Tuning, Monitoring, and Complex Systems for information about modifying system parameters.

Automatic changes between daylight saving time and standard time work only on OpenVMS Alpha Version 7.3. HP recommends that you do not enable automatic daylight saving time conversion on mixed-version or mixed-architecture OpenVMS Clusters.

Manually Adjusting for Daylight Saving Time on OpenVMS Version 7.3  

This section contains instructions for adjusting system time between standard time and daylight saving time on OpenVMS Version 7.3 when DTSS is not in use. Use these instruction for OpenVMS VAX Version 7.3 and for OpenVMS Alpha Version 7.3 when automatic daylight saving time switching is disabled (system parameter AUTO_DLIGHT_SAV is set to 0).

To adjust the local time to daylight saving time or standard time, invoke command procedure SYS$EXAMPLES:DAYLIGHT_SAVINGS.COM to perform both of the following tasks:

• Adjust the TDF



• Modify the local time by one hour forward or backward

DAYLIGHT_SAVINGS.COM allows you to perform either of the following actions:

• Make the changes immediately.



• Queue a batch job to make the changes at a future time. (This is the most common use of this command procedure.)

DAYLIGHT_SAVINGS.COM creates a command procedure, DST$CHANGE.COM, in the current directory. DST$CHANGE.COM can execute on the current node only. To change the time for all nodes in an OpenVMS Cluster, DAYLIGHT_SAVINGS.COM also creates command procedure DST$SYSMAN.COM that executes DST$CHANGE.COM by executing a SYSMAN DO command. Note that to change all nodes, you must run DAYLIGHT_SAVINGS.COM on a node that has OpenVMS Alpha Version 7.3 installed.

You can run DAYLIGHT_SAVINGS.COM interactively and respond to prompts for input, or run the command procedure with parameters.

To run DAYLIGHT_SAVINGS.COM with parameters, enter the following command:

$ @SYS$EXAMPLES:DAYLIGHT_SAVINGS P1 P2 P3 P4

P1	DAYLIGHT	Change from standard time to daylight saving time
	STANDARD	Change from daylight saving time to standard time
P2	NODE	Change time on this node only
	CLUSTER	Change time on the entire OpenVMS Cluster
P3	EXECUTE	Change time immediately
	QUEUE	Submit the job to SYS$BATCH for execution at the date and time specified by P4
	SAVE	Save the procedure for later modification
P4	date-time	If P3 is QUEUE, date and time that the submitted batch job is to run, in DD-MMM-YYYY:HH:MM:SS format; otherwise P4 is unused

Note that you need enter only the first letter of parameters P1, P2, and P3.

To run DAYLIGHT_SAVINGS.COM interactively, enter the following command:

$ @SYS$EXAMPLES:DAYLIGHT_SAVINGS

When executing DAYLIGHT_SAVINGS.COM to change the time on all nodes in an OpenVMS Cluster at a future time, you can specify SAVE for parameter P3. This causes DAYLIGHT_SAVINGS.COM to save command procedures DST$SYSMAN.COM and DST$CHANGE.COM. You can then submit DST$SYSMAN.COM to the correct queue.

Adjusting for Daylight Saving Time on OpenVMS Version 7.2  

This section contains instructions for adjusting system time for daylight saving time on OpenVMS Version 7.2 and earlier.

If you are using the Distributed Time Synchronization Service (DTSS), DTSS makes the necessary changes between daylight saving time and standard time. See Distributed Time Synchronization Service (DTSS).

• Adjust the TDF



• Modify the local time

DAYLIGHT_SAVINGS.COM allows you to perform either of the following actions:

• Make the changes immediately. (Usually, however, you would use UTC$TIME_SETUP.COM to make changes immediately by answering Yes to Question 5 in Setting the TDF on Your System.)



• Queue a batch job to make the changes at a future time. (This is the most common use of this command procedure.)

The following example of DAYLIGHT_SAVINGS.COM shows answers that cause the procedure to queue a batch job, DST_CHANGE, which will execute when the time changes from standard time to daylight saving time. Many of the questions are similar to those explained in Setting the TDF on Your System.

In the example, the initial TDF value is -5:00. The local date and time are any time from the date in 2000 when the change to standard time was made, until 1-APR-2001:02:00, when the change to daylight saving time will be made.

$ SYS$EXAMPLES:DAYLIGHT_SAVINGS
 
        This procedure queues a batch job that changes the system time
        and system time differential around a daylight saving time
        change.  Press the question mark (?) key at any time for help;
        hit Control-C to exit.
 
        The Time Differential Factor (TDF) is the difference
        between your system time and Coordinated Universal Time (UTC).
        The difference is expressed in hh:mm format.  The Americas
        have negative offsets from UTC, while Europe, Africa, Asia
        and Australia have positive offsets from UTC.
 
       * Enter the Time Differential Factor: -4:00 [Return]
 
        If this is a seasonal time change, it may also be
        necessary to modify the system time.  Generally,
        seasonal time changes result in adding 1:00 hour,
        or adding -1:00 hour to the local time.
 
        * Do you wish to modify the local system time [N]: Y [Return]
 
        Enter the time value you would like  to add to
        the local time.  The value can be a positive or
        a negative (-hh:mm) value.
 
        * Enter the time value: +1:00 [Return]
 
        The process to modify your time zone offset and local
        time (if supplied) can occur now or in the future.
        Press Return to run the job now.
 
        * Enter the run time in the DD-MMM-YYYY:HH:MM:SS format: 
01-apr-2001:02:00 [Return]
 
NEW SYSTEM TIME DIFFERENTIAL FACTOR = -4:00.
ADDING 1:00 TO THE LOCAL TIME.
JOB RUN TIME : 1-APR-2001:02:00
 
        * Continue? [Y]: Y [Return]
 
Job DST_CHANGE (queue SYS$BATCH, entry 2) holding until 1-APR-2001 02:00
Batch Job DST_CHANGE scheduled to run at 1-APR-2001:02:00
$
$!!The batch job DST_CHANGE will run on 1-Apr-2001 at 02:00

Setting Time in an OpenVMS Cluster Environment

Setting Time Using the Battery-Backed Watch (BBW) (Alpha Only)