Scenarios
These examples take place in the Pacific Time zone, where Pacific Daylight Time (PDT) is an hour later (ahead) of Pacific Standard Time (PST).
The official practice of observing daylight saving time is in the spring (generally in April), to move the time later (ahead) by one hour so that 2:00 A.M. PST will become 3:00 A.M. PDT.
In the autumn (in October), the time is moved one hour earlier (backwards) at 2:00 A.M. PDT to become 1:00 A.M. PST.
Each row in the following table is based on a time-initiated EXEC named BACKUP that has specified
- A start time when the EXEC should run
Either an end time when the EXEC should stop running or stop count (which specifies how many times the EXEC runs)
- An interval (20 minutes)
Daylight saving time examples
Scenario | If a time-initiated EXEC is scheduled to run | Column 1: Changing the MVS system clock forward from 2:05 A.M. to 3:05 A.M., the EXEC | Column 2: Changing the MVS system clock backward from 2:05 A.M. to 1:05 A.M., the EXEC |
|---|---|---|---|
A | Start time = 1:00 A.M. End time = 1:40 A.M. The EXEC should execute 3 times from 1:00 A.M. to 1:40 A.M. | Executes normally at
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT. | Executes a complete cycle at 1:00 A.M. PDT and a partial cycle after 1:05 A.M. PST, executing for a total of 5 times:
At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST and the EXEC begins executing again at
|
B | Start time = 1:00 A.M. End time = 2:20 A.M. The EXEC should execute 5 times from 1:00 A.M. to 2:20 A.M. | Executes a partial cycle at 1:00 A.M. and stops earlier than expected at 2:05 PST, executing only 4 times:
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute for the last time at 2:20 | Executes a partial cycle at 1:00 A.M. PDT and a partial cycle at 1:00 A.M. PST, executing for a total of 8 times:
At 2:05 PDT, the time changes backwards to 1:05 A.M. PST so the EXEC does not execute for the last time at 2:20. The EXEC starts executing again at
|
C | Start time = 1:00 A.M. Count = 5 Note that BMC AMI OpsA internally calculates that count = 5 is equivalent to specifying a stop time ending at 2:20 A.M. | Executes a partial cycle at 1:00 A.M. and stops earlier than expected at 2:05 PST, executing only 4 times:
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute for the last time at 2:20 | Executes a partial cycle at 1:00 A.M. PDT and a partial cycle at 1:00 A.M. PST, executing for a total of 8 times:
At 2:05 PDT, the time changes backwards to 1:05 A.M. PST so the EXEC does not execute for the last time at 2:20. The EXEC starts executing again at
|
Example for row C, column 1 EXEC: runs1 runs2 runs3 runs4 clock changes does not run PST 1:00am 1:20am 1:40am 2:00am 2:05am -------+-------+-------+-------+-------+-------+------+----- PDT 3:05am 3:10am 3:30am | |||
Example for row C, column 2 EXEC: runs1 runs2 runs3 runs4 clock runs5 runs6 runs7 runs8 changes PST 1:05am 1:20am 1:40am 2:00am 2:20am -------+------+------+------+------+------+------+------+------+--- PDT 1:00am 1:20am 1:40am 2:00am 2:05am | |||
D | Start time = 1:30 A.M. End time = 1:50 A.M. The EXEC should execute 2 times starting at 1:30 A.M. | Executes normally at
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT. | Executes through 2 complete cycles beginning at 1:30 A.M. PDT and again at 1:30 A.M. PST, executing for a total of 4 times:
At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST and the EXEC begins executing again at
|
E | Start time = 1:30 A.M. End time = 2:30 A.M. The EXEC should execute 4 times starting at 1:30 A.M. | Executes a partial cycle at 1:30 A.M. and stops earlier than expected, executing only 2 times:
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute for the last 2 times at 2:10 A.M. PST and 2:30 A.M. PST. | Executes a partial cycle at 1:30 A.M. PDT and executes a complete cycle at 1:30 A.M. PST, executing for a total of 6 times:
At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST and the EXEC begins executing again at
|
F | Start time = 1:30 A.M. End time = 3:30 A.M. The EXEC should execute 7 times starting at 1:30 A.M. | Executes a partial cycle at 1:30 A.M. and stops earlier than expected, executing only 4 times:
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute at 2:10, 2:30, and 2:50 A.M. PST but continues at
| Executes a partial cycle at 1:30 A.M. PDT and executes a complete cycle at 1:30 A.M. PST, executing for a total of 9 times:
At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST and the EXEC begins executing again at
|
G | Start time = 1:30 A.M. Count=5 | Executes a partial cycle at 1:30 A.M. and stops earlier than expected, executing only 2 times:
At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute for the last 3 times at 2:10, 2:30 and 2:50. | Executes a partial cycle at 1:30 A.M. PDT and executes a complete cycle at 1:30 A.M. PST, executing for a total of 7 times:
At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST and the EXEC begins executing again at
|
Example for row G, column 1 EXEC: runs1 runs2 clock changes PST 1:30am 1:50am 2:00am 2:05am -------+-------+-------+-------+-------+-------+------+----- PDT 3:05am 3:10am 3:30am 3:50 The EXEC runs for a total of 2 times. | |||
H | Start time = 2:30 A.M. End time = 2:50 A.M. The EXEC should execute 2 times starting at 2:30 A.M. | Does not execute at all as the clock time is changed At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute at 2:30 or 2:50. | Executes through 1 complete cycle but the cycle begins 3.5 hours after midnight instead of 2.5 hours after midnight At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST so the EXEC does not run at 2:30 PDT but when the time becomes 2:30 A.M. PST, the EXEC begins executing at
|
I | Start time = 2:30 A.M. End time = 3:50 A.M. The EXEC should execute 5 times starting at 2:30 A.M. | Executes a partial cycle executing 3 times starting at 3:10 A.M. PDT At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute at 2:30, 2:50 A.M. and starts to run at
| Executes through 1 complete cycle but the cycle begins 3.5 hours after midnight instead of 2.5 hours after midnight At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST so the EXEC does not run at 2:30 PDT but when the time becomes 2:30 A.M. PST, the EXEC begins executing at
|
J | Start time = 2:30 A.M. Count = 2 | Does not execute at all as the clock time is changed: At 2:05 A.M. PST, the time changes to 3:05 A.M. PDT so the EXEC does not execute at 2:30 and 2:50 A.M. in the morning. | Executes through 1 complete cycle but the cycle begins 3.5 hours after midnight instead of 2.5 hours after midnight At 2:05 A.M. PDT, the time changes backward to 1:05 A.M. PST so the EXEC does not run at 2:30 but when the time becomes 2:30 A.M. PST, the EXEC begins executing at
|