Updated: 11 December 1998 |
OpenVMS System Manager's Manual
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One of the steps in setting the correct time on your system is to calculate a time differential factor (TDF) for your time zone.
The TDF associates each local time zone with UTC; it is the difference between your local system time and UTC. The TDF changes each time your local system time undergoes a time zone change; the UTC, on the other hand, does not change.
The TDF value is expressed in signed (+ or -) hh:mm format. The Americas have negative TDFs, while Europe, Africa, Asia, and Australia have positive TDFs.
Section 5.9.2 explains how to select the correct TDF for your time zone.
5.9.1.3 Daylight Saving Time and Standard Time
Typically, you make seasonal changes to the local system time (for example, for daylight saving time and standard time). You usually adjust the local time one hour forward or backward.
You also need to adjust the TDF to compensate for the new local system
time. You adjust the TDF in the same direction as the local time; that
is, when you add an hour to the local time, you also add an hour to the
TDF.
5.9.1.4 Time Zones
Time zones are names for geographical areas that share the same TDF;
they also share the same rule or rules for seasonal changes between
standard time and daylight saving time.
5.9.2 Determining Your System's Time Differential Factor
You can use the map in Figure 5-1 to determine the TDF for your time zone. If you prefer, you can use the tables in Appendix B in the OpenVMS System Manager's Manual to determine the standard or daylight saving time TDF for your time zone. The procedure described in Section 5.9.3 shows default TDF values for various time zones.
To use the map to determine the TDF of your time zone, follow these steps:
Some time zones do not have full-hour TDFs. In these cases, find the specific value on the map itself. For example, if you live in Adelaide, Australia, your TDF is +9:30.
If your time zone has daylight saving time, your TDF for daylight saving time is typically +1:00 from the standard time. For example, if your standard time TDF is +2:00, your daylight saving time TDF is +3:00; if your standard time TDF is -7:00, your daylight saving time TDF is -6:00.
Figure 5-1 Time Differential Factor Map
5.9.3 Using UTC$TIME_SETUP.COM
You can use this command procedure in the following ways:
If you set the time zone and the TDF on one node in a cluster, the values you set take effect on other nodes in the cluster when those nodes are rebooted.
For your convenience, the instructions for using the command procedure have been split into two sections:
To use SYS$MANAGER:UTC$TIME_SETUP.COM, follow these steps:
$ SET PROCESS/PRIVILEGES=(LOG_IO,OPER) |
$ @SYS$MANAGER:UTC$TIME_SETUP.COM |
%UTC-I-UPDTIME, updating Time Zone information in SYS$COMMON:[SYSEXE] |
Configure which time parameter (TIMEZONE/TDF/BOTH/NONE)? [BOTH] |
Compaq recommends that you set both the time zone and the TDF. If you set the TDF without setting the time zone, the procedure cannot provide default TDF values. |
If you answer BOTH or TIMEZONE to the time parameter question in the
command procedure, continue with the next section. If you answer TDF to
the question, skip to Section 5.9.3.2.
5.9.3.1 Setting the Time Zone on Your System
The local time zone is the location you want to consider your default local time zone. Usually this local time zone is the same as the local time zone in which your system is located.
You set the local time zone by making choices in a command procedure.
The system first displays the following information:
Configuring the Local Time Zone TIME ZONE SPECIFICATION -- Main Time Zone Menu 1) Australia 11) GMT 21) Mexico 31) Turkey 2) Brazil 12) Greenwich 22) NZ 32) UCT 3) CET 13) Hong Kong 23) NZ-CHAT 33) US 4) Canada 14) Iceland 24) Navajo 34) UTC 5) Chile 15) Iran 25) PRC 35) Universal 6) Cuba 16) Israel 26) Poland 36) W-SU 7) EET 17) Jamaica 27) ROC 37) WET 8) Egypt 18) Japan 28) ROK 38) Zulu 9) Factory 19) Libya 29) Singapore 10) GB-Eire 20) MET 30) SystemV 0) None of the above |
Table 5-5 lists and describes the acronyms that appear in the Main Time Zone Menu.
Time Zone Acronym | Description |
---|---|
CET | Central European Time |
EET | Eastern European Time |
Factory | Specifies no time zone |
GB-Eire | Great Britain/Ireland |
GMT | Greenwich Mean Time |
MET | Middle European Time |
NZ | New Zealand |
NZ-CHAT | New Zealand, Chatham Islands |
PRC | People's Republic of China |
ROC | Republic of China |
ROK | Republic of Korea |
SystemV | Specific to System V operating system |
UCT | Coordinated Universal Time |
US | United States |
UTC | Coordinated Universal Time |
Universal | Coordinated Universal Time |
W-SU | Middle European Time |
WET | Western European Time |
To select a time zone, follow these steps:
Select the number above that best describes your location: 33 |
You selected US as your time zone. Is this correct? (Yes/No) [YES]: [Return] |
US Time Zone Menu 1) Alaska 4) Central 7) Hawaii 10) Mountain 2) Aleutian 5) East-Indiana 8) Indiana-Starke 11) Pacific 3) Arizona 6) Eastern 9) Michigan 12) Samoa 0) None of the above |
Select the number above that best describes your location: 6 |
You selected US/Eastern as your time zone. Is this correct? (Yes/No) [YES]: [Return] |
Default Time Differential Factor for standard time is -5:00. *Default Time Differential Factor for daylight saving time is -4:00. |
If you answer TDF or BOTH to the time parameter question at the beginning of the command procedure, the system displays prompts for the TDF on your system.
To set the TDF, answer the following questions:
Configuring the Time Differential Factor (TDF) Enter ? anytime for help [0] Exit [1] Set the Time Differential Factor [2] Display the Time Differential Factor |
Please pick an option number [2]: 2 |
SYSTEM TIME DIFFERENTIAL FACTOR = -4:00 (-14400 seconds). LOCAL SYSTEM TIME = 22-SEP-1998 10:49:45.20. |
Configuring the Time Differential Factor (TDF) Enter ? anytime for help [0] Exit [1] Set the Time Differential Factor [2] Display the Time Differential Factor |
Please pick an option number [2]: 1 |
The Time Differential Factor (TDF) is the difference between your system time and Coordinated Universal Time (UTC). UTC is similar in most repects to Greenwich Mean Time (GMT). The TDF is expressed as hours and minutes, and should be entered in the hh:mm format. TDFs for the Americas will be negative (-3:00, -4:00, etc.); TDFs for Europe, Africa, Asia and Australia will be positive (1:00, 2:00, etc.). |
Is Daylight Saving time in effect? (Yes/No): |
Enter the Time Differential Factor [-4:00]: |
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 system time. |
Do you wish to modify the local system time [N]: |
NEW SYSTEM TIME DIFFERENTIAL FACTOR = -4:00. |
Is this correct? [Y]: |
SYSTEM TIME DIFFERENTIAL FACTOR = -4:00 (-14400 seconds). LOCAL SYSTEM TIME = 22-SEP-1998 10:52:37.36. |
To adjust the local time to daylight saving or standard time, you can invoke the command procedure SYS$EXAMPLES:DAYLIGHT_SAVINGS.COM to perform both of the following tasks:
DAYLIGHT_SAVINGS.COM allows you to perform either of the following actions:
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 Section 5.9.3.2.
In the example, the initial TDF value is -5:00. The local date and time are any time from the date in 1997 when the change to standard time was made, until 23-APR-1998:02:00, when the change to daylight saving time will be made.
$ SYS$EXAMPLES:DAYLIGHT_SAVINGS This procedure queues a batch job that changes the system time and system time differential around a daylight saving time change. Press the question mark (?) key at any time for help; hit Control-C to exit. The Time Differential Factor (TDF) is the difference between your system time and Coordinated Universal Time (UTC). The difference is expressed in hh:mm format. The Americas have negative offsets from UTC, while Europe, Africa, Asia and Australia have positive offsets from UTC. * Enter the Time Differential Factor: -4:00 [Return] If this is a seasonal time change, it may also be necessary to modify the system time. Generally, seasonal time changes result in adding 1:00 hour, or adding -1:00 hour to the local time. * Do you wish to modify the local system time [N]: Y [Return] Enter the time value you would like to add to the local time. The value can be a positive or a negative (-hh:mm) value. * Enter the time value: +1:00 [Return] The process to modify your time zone offset and local time (if supplied) can occur now or in the future. Press Return to run the job now. * Enter the run time in the DD-MMM-YYYY:HH:MM:SS format: 23-apr-1998:02:00 [Return] NEW SYSTEM TIME DIFFERENTIAL FACTOR = -4:00. ADDING 1:00 TO THE LOCAL TIME. JOB RUN TIME : 23-APR-1998:02:00 * Continue? [Y]: Y [Return] Job DST_CHANGE (queue SYS$BATCH, entry 2) holding until 23-APR-1998 02:00 Batch Job DST_CHANGE scheduled to run at 23-APR-1998:02:00 $ $!!The batch job DST_CHANGE will run on 23-Apr-1998 at 02:00 |
The TDF and the local time must be the same on all nodes in an OpenVMS Cluster environment. You can use the System Management utility (SYSMAN) DO command to invoke the command procedure UTC$CONFIGURE_TDF.COM on one node in a cluster to perform the following actions for one or more nodes in the cluster:
Note that UTC$CONFIGURE_TDF.COM is normally run by UTC$TIME_SETUP.COM when you select the TDF or BOTH option.
You specify the function SET or SHOW, the TDF value, and the local time modification as command procedure parameters. Note that you must express the TDF and the change to the local time in minutes format, not in hours and minutes hh:mm format, as you do if you use the command procedure interactively. For example, for +2:00, you would enter +120 or 120.
$ RUN SYS$SYSTEM:SYSMAN SYSMAN> SET ENVIRONMENT/CLUSTER |
%SYSMAN-I-ENV, Current command environment: Clusterwide on local cluster Username SMITH will be used on nonlocal nodes |
SYSMAN> DO @SYS$MANAGER:UTC$CONFIGURE_TDF SET +660 +60 |
$ RUN SYS$SYSTEM:SYSMAN SYSMAN> SET ENVIRONMENT/CLUSTER |
%SYSMAN-I-ENV, Current command environment: Clusterwide on local cluster Username SMITH will be used on nonlocal nodes |
SYSMAN> DO @SYS$MANAGER:UTC$CONFIGURE_TDF SHOW |
$! TO_STANDARD_TIME.COM $! Command procedure to change the TDF by -1:00 and also modify local time $ RUN SYS$SYSTEM:SYSMAN SET ENVIRONMENT/CLUSTER DO @SYS$MANAGER:UTC$CONFIGURE_TDF SET -270 -60 EXIT |
$ SUBMIT/AFTER=23-JAN1998:02:00 TO_STANDARD_TIME.COM |
The OpenVMS Alpha architecture maintains the current date and time in the Battery-Backed Watch (BBW) across power failures and system downtime. The BBW is functionally equivalent to the Time of Day Register (TODR) that the VAX architecture uses. One difference, however, is the BBW's constraint on the date range.
The BBW provides sufficient storage capability for only a century. The OpenVMS Alpha system date range has been redefined as 1957 to 2056 to maintain correct leap-year processing and to provide for the millennial transition.
In addition, the OpenVMS Alpha timing mechanisms have been changed to allow 2-digit year support in the $ASCTIM system service and the DCL command SET TIME. (Prior to this change, only 4-digit year fields were allowed.) With 2-digit support, you need to enter only the last 2 digits of a year. The century associated with the year field is derived from the placement of the 2 digits in the 1957-2056 date range. For example:
$ SET TIME = 1-NOV-98 |
In this example, 98 is the equivalent of 1998.
$ SET TIME = 1-NOV-05 |
In this example, 05 is the equivalent of 2005.
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