• In-progress jobs marked recoverable are automatically re-executed after a scheduler fails. This means some of the job's work will be executed twice, so the job should be coded in such a way that its work is idempotent.
• Avoid scheduling any jobs during the Daylight Savings Time (DST) interval. SimpleTriggers are not affected by DST as they always fire at an exact millisecond in time and repeat an exact number of milliseconds apart. Because CronTriggers fire at given hours/minutes/seconds, they are subject to some oddities when DST transitions occur.

As an example of possible issues, when scheduling in the United States within time zones /locations that observe DST, the following problems may occur if using CronTrigger and scheduling fire times from 1:00 AM to 2:00 AM:

• 1:05 AM may occur twice–duplicate firings on CronTrigger possible
• 2:05 AM may never occur–missed firings on CronTrigger possible