Planned Maintenance of network devices forms an integral part of network administration. You may want to perform a maintenance of specific device types at specific intervals. If such devices are removed from the network, or rebooted, then you will see alarms indicating that the device, or the applications in the device are unavailable. Since the devices are not available when polled for status during the maintenance period, unnecessary alarms are fired. To prevent the devices from being monitored for status during maintenance, you can schedule a maintenance task for such devices.
If you wish to disable the device downtime schedule, go to Settings -> Configuration -> Device Downtime Schedules and set the status as disable for the corresponding downtime schedule.