Table of Contents Executive Summary 3

2.2CMS

In addition to common interfaces, OSG has provided the packaging, configuration, and support of the storage services. Since the beginning of OSG the operations of storage at the Tier-2 centers have improved steadily in reliability and performance. OSG is playing a crucial role here for CMS in that it operates a clearinghouse and point of contact between the sites that deploy and operate this technology and the developers. In addition, OSG fills in gaps left open by the developers in areas of integration, testing, and tools to ease operations. The stability of the computing infrastructure has not only benefitted CMS. CMS’ use of resources (see Error: Reference source not found and Error: Reference source not found) has been very much cyclical so far, thus allowing for significant use of the resources by other scientific communities. OSG is an important partner in Education and Outreach, and in maximizing the impact of the investment in computing resources for CMS and other scientific communities.

In addition to computing infrastructure OSG plays an important role in US-CMS operations and security. OSG has been crucial to ensure US interests are addressed in the WLCG. The US is a large fraction of the collaboration both in terms of participants and capacity, but a small fraction of the sites that make-up WLCG. OSG is able to provide a common infrastructure for operations including support tickets, accounting, availability monitoring, interoperability and documentation. As CMS has entered the operations phase, the need for sustainable security models and regular accounting of available and used resources has become more important. The common accounting and security infrastructure and the personnel provided by OSG represent significant benefits to the experiment, with the teams at Fermilab and the University of Nebraska providing the development and operations support, including the reporting and validation of the accounting information between the OSG and WLCG.


CMS

Figure : OSG CPU hours used by CMS (63M hours total), color coded by facility.

Figure : Number of unique CMS users of the OSG computing facility.

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  Within the last year, CMS transitioned to using glideinWMS in production for both reprocessing at the Tier-1s as well as analysis at the Tier-2s and Tier-3s. Burt Holzman at Fermilab and Igor Sfiligoi at UCSD have been spearheading these efforts. OSG has been crucial in providing expertise during deployment and integration, and working with the Condor team on resolving a variety of scalability issues within glideinWMS. In addition, OSG provided developer expertise towards the integration of glideinWMS with the CMS data analysis framework, CRAB. The next steps in this area are to work out deployment issues with CERN. Through the leadership of Frank Wuerthwein at UCSD OSG is working with DISUN and Condor on a more firewall friendly glideinWMS, a requirement for CERN deployment as well as to overcome the next set of scalability hurdles.
  
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  OSG’s introduction of lcg-cp/ls/rm, UberFTP, and MyProxy into the VDT client installation has eliminated the dependencies on the gLite middleware at CMS sites, thus significantly simplifying deployment and operations of the sites.
  
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  The OSG work on CE scalability and robustness has made CE overloads a rare occurrence at present scales for CMS. The only time we still experience this as a problem is when VOs other than CMS use our sites in non-optimal ways.
  
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  The investment by the OSG storage team, led by Tanya Levshina at Fermilab, in support of BeStMan SRM is an excellent example where OSG provided something requested by stakeholders other than CMS, but that has proven to be very beneficial to CMS. CMS now deploys BeStMan, supported through OSG’s Alex Sim who is a member of Arie Shoshani’s team at LBNL, as part of the preferred Storage Element (SE) solution at Tier-3s, as well as a high performance SE option for the Tier-2s. The latter in combination with HDFS or Lustre as file systems, reaching 100Hz lcg-ls rates during scalability tests done by OSG at three of the CMS Tier-2 sites. This is a 20x increase within the last year. OSG has recently been starting to include integration and deployment support for the complete package of BeStMan/gridFTP/Fuse/HDFS for use at Tier-2s and Tier-3s. Without OSG, this kind of “technology transfer” into CMS would not have happened.
  
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  OSG, through the contributions of Brian Bockelman at the University of Nebraska working with the CMS and OSG storage teams, has contributed to an improved understanding of the IO characteristic of CMS analysis jobs, and is providing advice and expertise to an effort in global CMS of measuring the IO capability of all of the CMS sites worldwide. OSG helped get this activity off the ground in global CMS, with an expectation that lessons learned will flow back to OSG to be disseminated to the wider OSG community. The CMS goal here is to improve the CPU efficiency for data analysis at Tier-2s and Tier-3s worldwide. We expect this activity to continue well into 2010.