8.9.4 Using JP1/AJS3 in a time zone with daylight saving time

When you use JP1/AJS3 in a time zone where daylight saving time applies, the following start times are affected:

Start times of jobnets registered for execution by JP1/AJS3 - View
Start times of jobnets registered for execution by the ajsentry command
Start times of submits jobs registered by the jpqjobsub command with the -st option specified
Start times of processing to delete job information

The following describes the effects of switching from standard time to daylight saving time, and vice versa. Take these effects into consideration when you define the start times for each process. The following figure uses Eastern U.S. standard time in 1994 (TZ=EST5EDT) as an example of a time zone with daylight saving time.

Figure 8‒22: Example of switching between standard time and daylight saving time

Organization of this subsection

(1) Switching from standard time to daylight saving time
(2) Switching from daylight saving time to standard time

(1) Switching from standard time to daylight saving time

The timing with which processes start after the system switches from standard time to daylight saving time is determined from the start time set for the process, and the time at which the transition from standard time to daylight saving time takes place. The following explanation is based on the example shown in Figure 8-22. When the time reaches 2:00:00 on April 7th, the clock switches to daylight saving time. At this point, the new time will be 3:00:00 on April 7th (this is transition (1) 4/7 1:59:59 [Figure] 4/7 3:00:00 in Figure 8-22). This means that the period from 2:00:00 to 2:59:59 is skipped over. If you set up a process to start within this period, it will start at 3:00:00 daylight saving time. If you set it up to start at 3:00:00 or later standard time, the process will start at 3:00:00 or later after the transition to daylight saving time has taken place. This means that the process will start, in relative terms, one hour ahead of its scheduled start time. The following table shows how processes are scheduled around the transition from standard time to daylight saving time.

Table 8‒8: Scheduling at the transition from standard time to daylight saving time
Start time setting	1:59:59 or earlier	2:00:00 to 2:59:59	3:00:00 or later
Actual start time	Executed at 1:59:59 or earlier standard time	Executed at 3:00:00 daylight saving time	Executed at 3:00:00 or later daylight saving time

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(2) Switching from daylight saving time to standard time

The timing with which processes start after the system switches from daylight saving time to standard time is determined from the start time set for the process, and the time at which the transition from daylight saving time to standard time takes place. The following explanation is based on the example shown in Figure 8-22. When the time reaches 2:00:00 (DST) on October 27th, the clock switches to standard time. At this point the new time will be 1:00:00 standard time on October 27th (this is transition (2) 10/27 1:59:59 [Figure] 10/27 1:00:00 in Figure 8-22). The result is an extra hour in standard time, from 1:00:00 to 2:00:00. However, processes that were scheduled to start between 1:00:00 and 1:59:59 are started at the scheduled time in daylight saving time, and are not started again after the transition from daylight saving time to standard time. If you set up a process to start at 2:00:00 daylight saving time or later, it will start at 2:00:00 in standard time, after the transition from daylight saving time to standard time has taken place. This means that the process will start, in relative terms, one hour later than its scheduled start time. The following table shows how processes are scheduled around the transition from daylight saving time to standard time.

Table 8‒9: Scheduling at the transition from daylight saving time to standard time
Start time setting	0:59:59 or earlier	1:00:00 to 1:59:59	2:00:00 or later
Actual start time	Executed at 0:59:59 daylight saving time or earlier	Executed between 1:00:00 and 1:59:59 daylight saving time	Executed at 2:00:00 standard time or later

Cautionary notes

If JP1/AJS3 - View and JP1/AJS3 - Manager run on different hosts, make sure that both hosts use the same time zone. For details, see 2.2.2(2) Operation with multiple manager hosts in the Job Management Partner 1/Automatic Job Management System 3 System Design (Configuration) Guide and Cautionary notes in 4.2.1 Types of JP1/AJS3 services in the Job Management Partner 1/Automatic Job Management System 3 System Design (Configuration) Guide.
When you use the ajsentry command to register a jobnet for execution, the schedule of the jobnet depends on the time zone setting used when you execute the ajsentry command. For details, see 2.2.2(2) Operation with multiple manager hosts in the Job Management Partner 1/Automatic Job Management System 3 System Design (Configuration) Guide.
When you register a submit job for execution using the jpqjobsub command with the -st option specified, the job's start time depends on the time zone setting of the manager host that registers the job.

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