Experience with the custom-developed ATLAS offline trigger monitoring framework and reprocessing infrastructure

The offline trigger monitoring of the ATLAS experiment is assessing the data quality and analyses those events where no trigger decision could be made. Within the offline monitoring, which is started shorty after the data acquisition has finished, the online data quality assessment is reflected. Additionally, a reprocessing system tests changes to the trigger software and configuration to ensure their stability and reliability before they can become operating. This note explains the activities performed to provide a flawless monitoring of the operation of the ATLAS trigger system and how to assess the quality of the recorded data.