We noticed that on our monitor there is a large check gap between 00:58 – 03:00. The monitor is not in any maintenance mode nor was it turned off by anyone. What could have caused this gap in checks?
While investigating the Monitor configuration, it was found that the Check Periods were set to start at 3:00 AM and end at 1:00 AM.
How ASM interprets this is the following:
Run the checks starting at 3:00 AM today and run until 1:00 AM the next morning. And then between 1:00 AM the next morning to 3:00 AM the next morning, no checks will be executed for this monitor.
So the monitor was working as it was configured to, which is why there was a gap in checks between 1:00 AM and 3:00 AM.
If you want to run checks 24/7, then the best way to configure the check time period is from 00:00 to 23:59. This way the checks run all the time without any gaps.