The maintenance_mode probe sets user-specified maintenance windows for devices. During these maintenance windows, only informational and clear alarm messages are displayed during a maintenance window. QoS collected by the probes are still inserted into the database and will be incorporated in the the configured SLAs.
In order to exclude the QoS during the 24 hour maintenance windows, it is necessary to set up excluded periods—for instance, for system maintenance or business holidays— in the SLA compliance period of the SLAs you create. See the Create a New Service Level Agreement->Create a New SLA Wiki page for a discussion on setting up a compliance period in your SLAs.