COMPUTING

Computing operation has been lower as the Run 1 samples are completing and smaller samples for upgrades and preparations are ramping up. Much of the computing activity is focusing on preparations for Run 2 and improvements in data access and flexibility of using resources.

Operations Office

Data processing was slow in the second half of 2013 with only the legacy re-reconstruction pass of 2011 data being processed at the sites.

 

Figure 1: MC production and processing was more in demand with a peak of over 750 Million GEN-SIM events in a single month.

 

Figure 2: The transfer system worked reliably and efficiently and transferred on average close to 520 TB per week with peaks at close to 1.2 PB.

 

Figure 3: The volume of data moved between CMS sites in the last six months

 

The tape utilisation was a focus for the operation teams with frequent deletion campaigns from deprecated 7 TeV MC GEN-SIM samples to INVALID datasets, which could be cleaned up. This allowed CMS to stay at below 90% of the tape pledges. But continuous clean up will be needed in 2014 and beyond to maximise the usefulness of the occupied tape space. The new Tier-1 site in Russia is coming online and is now used routinely for MC production. Additional T3 sites request to be added to the CMS computing systems as well. In 2014, CMS computing will concentrate on integration of new systems like the full deployment of the CMS data federation (AAA) and the finalisation of system implementations like the global GlideInWMS condor pool. A major focus will be the efficiency and latency of the systems like the latency for workflows in the production system.

Computing Development

The Computing Development project has concentrated on completing the CRAB3 prototype for analysis users. The final effort is on the data publication step. A production release in expected in the spring of 2014. Additionally there has been effort on planning for the transition from the dataset bookkeeping system version 2 to version 3.

Computing Evolution and Upgrade

The resources of the CMS online HLT farm completed the first validated production workflows for reconstruction and the HLT was certified for offline computing activity. The HLT has demonstrated the use of 6000 running cores reading data from EOS in the Tier-0. This resource will be critical to reprocessing the 2015 data.

Computing Integration

Computing Integration has concentrated on testing the new CRAB3 analysis submission tool. When the next version of CMSSW, which supports event level parallelism, is released integration will have an intensive period of commission as the experiment moves to multi-core for production resources.

Physics Support

CMS held its first Data Analysis School (CMSDAS) in India during 7-11 November 2013. About 25 Facilitators (teachers) came to the Saha Institute, Kolkata, India to get 40 students (India, Malayaisa, Taiwan) ready for the 2015 physics analysis. This was made possible by the generous travel support from LPC (Fermilab), CERN, DESY and Taiwan. January 2014 will mark two more CMS Data Analysis Schools – LPC, Fermilab (7–11 January) and CERN (13–17 January). The latter will be the first CMSDAS hosted at CERN. Over 100 students are expected to attend the two schools.

A new automated tool – Data format viewer – was developed showing information about CMSSW data formats. This replaces the Twikis used so far for the same purpose.

One year after RemoteGlideIn scheduler was introduced in CRAB2  almost all users have turned to it and Physics Support could turn off the last CRAB2 server last August. Support for submission via gLite is also ramping down and will terminate in 2014 while we focus in commissioning the new CRAB3-based analysis tool. It is interesting to note that currently almost all analysis jobs failures are due to either stage-out problems or to job hitting time or memory limits.

 

Figure 4: The evolution of the percentage of analysis submission by interface

Computing Resource Management Office

The Mid-2013 Resource Utilization Report and the Extra Resource Request Report were submitted to the Computing Resource Scrutiny Group and reviewed in the fall. The computing requests for 2015 were endorsed by the scrutiny group.

The Mid-2013 Resource Utilization Report and the Extra Resource Request Report were submitted to the Computing Resource Scrutiny Group and reviewed in the fall. The computing requests for 2015 were endorsed by the scrutiny group.


by I. Fisk, M. Girone, D. Bonacorsi, O. Gutsche, C. Paus, S. Belforte, J. Letts, S. Malik, J. Hernandez Calama, C. Wissing, D. Colling, G. Grandi and P. Kreuzer.