by Daniele De Gruttola & Barthelemy Von Haller. Published: 27 May 2015

Data Quality Monitoring (DQM) is an important aspect of every high-energy physics experiment. In the era of LHC, when the detectors are extremely sophisticated devices, an online feedback on the quality of the data recorded is needed to avoid taking low quality data and to guarantee a good baseline for offline analysis.

The software used in ALICE is called AMORE (Automatic MOnitoRing Environment) and provides the above mentioned feedback, helping shifters and experts to identify potential issues in advance. DQM involves the online gathering of data, their analysis by user-defined algorithms and the storage and visualization of the produced monitoring information.

AMORE is based on the widely-used data analysis framework ROOT [1] and uses the DATE (Data Acquisition and Test Environment) [2] monitoring library. Automatic DQM requires a many-to-many client-server paradigm in order to serve the several monitoring needs and make possible such advanced functionalities as fast reconstruction or correlation between different detectors. A large number of processes, named agents, execute detector-specific decoding and analysis on raw data samples and publish their results in a pool. Clients can then connect to the pool and visualize the monitoring results through a dedicated user interface. The pool is implemented as a database.

Plot generated by one of the DAQ AMORE modules to monitor the data size of the detectors over time.

The open-source MySQL system was chosen as it proved to be reliable, performant and light-weight. The database contains a table with a list of all the agents, specifying on which machine they are allowed to run and to which detector they belong. Another table contains configuration files, that are optional and allow each detector to define, by instance, different configurations  corresponding to different run types. Finally, a data table is created for each agent where the published objects are stored. The subscriber part of the users’ modules mainly consists of a Graphical User Interface (GUI) capable of handling the objects produced by the publishing part. As the basic needs of most of the detectors teams were very similar, a generic GUI has been developed in order to avoid code duplication and ease users’ lives.

The GUI can be used to browse and visualize any object of any running agent. An access through the web, thanks to the ALICE electronic logbook, provides experts with an easy way to look at the monitoring histograms from outside the Control Room. AMORE is capable to access a small part of the raw data and perform some online analysis, that in the past required much longer, giving a crucial feedback on the quality of the data. During Run1 DQM was  successfully used to spot issues and avoid recording bad quality data.

The work performed during LS1 has been devoted to the improvement of several aspects, like the increase in automatic checks, the integration of new systems, such as DCal and AD, the optimization of the online Event Display and the addition of new useful plots to be monitored by shifters. Continuous interactions between the users and the framework developers are one of the most important aspects since the beginning of the AMORE development and currently during Run2, in order to guarantee good performance of the ALICE DQM, that has to handle 19 detectors and DAQ, HLT and Trigger systems.

 

[1] Brun R and Rademakers F 1997 ROOT - An object oriented data analysis framework Nuclear instruments and methods in physics research A389 pp 81-86

[2] The ALICE DAQ Project 2006 ALICE DAQ and ECS User’s Guide CERN

 

Comments

DQM shifts

<p>It was my priviledged type of shifts at Alice which I will keep in memory for a long time...</p>