Xrootd Monitoring for the CMS Experiment

L A T Bauerdick, K Bloom, B Bockelman, D C Bradley, S Dasu, I Sfiligoi, A Tadel, M Tadel, F Wuerthwein, A Yagil
2012 Journal of Physics, Conference Series  
During spring and summer of 2011, CMS deployed Xrootd-based access for all US T1 and T2 sites. This allows for remote access to all experiment data on disk in the US. It is used for user analysis, visualization, running of jobs at computing sites when data is not available at local sites, and as a fail-over mechanism for data access in jobs. Monitoring of this Xrootd infrastructure is implemented on three levels. Basic service and data availability checks are performed by Nagios probes. The
more » ... nd level uses Xrootd's "summary data" stream; this data is aggregated from all sites and fed into a MonALISA service providing visualization and storage. The third level uses Xrootd's "detailed monitoring" stream, which includes detailed information about users, opened files and individual data transfers. A custom application was developed to process this information. It currently provides a real-time view of the system usage and can store data into ROOT files for detailed analysis. Detailed monitoring allows us to determine dataset popularity and to detect abuses of the system, including sub-optimal usage of the Xrootd protocol and the ROOT prefetching mechanism. Published under licence by IOP Publishing Ltd
doi:10.1088/1742-6596/396/4/042058 fatcat:o5d56vmu4vd3bjxgbjw5o5xfii