Clock change problems with the switch off Daylight Savings Time (in the Fall)
- Article Type: Q&A
- Product: Aleph
- Product Version: 20, 21, 22, 23
Question
What can we do to prevent problems with the switch off Daylight Savings Time (in the Fall)?
What should we do if we have problems?
Answer
The critical element is the job daemon.
If the job daemon is running at the time the change occurs, all job_list jobs will run twice from that time on, one hour apart.
Running some jobs twice is not a problem, but others -- such as the "Overdue notices (cir-51/cir-52) -- results in blank output from the second run overwriting valid output from the first. (Note: If the print daemon is running at the time the first execution of cir-51/cir-52 occurs, then the notices will be printed/emailed, and there won't be any real problem.)
Note: In another case the job daemon stopped executing certain jobs at all.
The solution, in evey case, is to stop/restart the job daemon!!!
To prevent this, you need to stop the job daemon (util e/15/2) prior to the time that the first jobs are scheduled to run after the time change.
Then restart it (util e/15/1) after the time change. The article " csh command to start job daemon " has a crontab script to perform the restart.
Additional Information
* If you don't have any job_list jobs scheduled to run between 1 a.m.* Sunday morning (which is the time it falls back to in the Fall) and, say, 9 a.m., when you will connect to the system to stop/start the job daemon, then you should be able to leave the job daemon running during the time change and restart it at 9 am before any jobs run in the morning.
On the other hand, if you have job_list jobs which run at 1 a.m.*, 3 a.m., or 6 a.m., you will need to stop the job daemon before the 2 a.m. time change and restart it after.
If you fail to stop/start the job daemon and have problems, you should immediately stop/start the job daemon -- no matter how much time has elapsed since the time change.
* If you have the problem with "Overdue notices (cir-51)", you can use the document "How To Re-run p_cir_51" in Documentation Center (and attached to this Article) to reproduce the output. It applies equally to cir-50 and cir-52.
* For the change to Daylight Savings Time consult article "Clock Change: Change to Daylight Savings Time (in the Spring)" (KB 8192-743)