ATLAS off-Grid sites (Tier 3) monitoring. From local fabric monitoring to global overview of the VO computing activities

ATLAS is a particle physics experiment on Large Hadron Collider at CERN. The experiment produces petabytes of data every year. The ATLAS Computing model embraces the Grid paradigm and originally included three levels of computing centres to be able to operate such large volume of data. With the formation of small computing centres, usually based at universities, the model was expanded to include them as Tier3 sites. The experiment supplies all necessary software to operate typical Grid-site, but Tier3 sites do not support Grid services of the experiment or support them partially. Tier3 centres comprise a range of architectures and many do not possess Grid middleware, thus, monitoring of storage and analysis software used on Tier2 sites becomes unavailable for Tier3 site system administrator and, also, Tier3 sites activity becomes unavailable for virtual organization of the experiment. In this paper we present ATLAS off-Grid sites monitoring software suite, which enables monitoring on sites, which are not under operation of ATLAS Distributed Computing software