GDB, 07/06/06 CMS Centre Roles à CMS data hierarchy: n RAW (1.5/2MB) -> RECO (0.2/0.4MB) -> AOD (50kB)-> TAG à Tier-0 role: n First-pass reconstruction RAW -> RECO; curation / distribution to T1 à Tier-1 roles: n Custodial storage of RAW data (one copy split across all T1) n Storage of RECO fraction and full AOD for fast access n nth-pass reconstruction (three times per year) n Physics group bulk analysis / skimming n Data serving to and receipt from T2 à Tier-2 roles: n End-user analysis; Simulation capacity n Possibility of special functions (calibration, HI reconstruction) à CTDR assumed roughly hierarchical T1-T2 relationship

GDB, 07/06/06 CMS T1 Sites à ‘Nominal Tier-1’ size in 2008: n 2.5MSI2K CPU / 1.2PB disk / 2.8PB tape n Computing model assumed 6-7 nominal sites à Current CMS T1 sites n France (CCIN2P3) - 60% nominal* n Germany (GridKa) - 50% nominal* n Italy (CNAF) - 75% nominal* n Spain (PIC) - 30% nominal* n Taiwan (ASCC) - 60% nominal* n UK (RAL) - 20% nominal; 60% nominal requested by 2008 n US (FNAL) - 170% nominal n *Note also - 65% total shortfall in tape in non-US centres n Look to correct this through rebalancing of centre resources

GDB, 07/06/06 CMS T2 Sites and Affiliations CountryT2 sitesT1CountryT2 sitesT1 Belgium1 federatedIN2P3Italy4CNAF Brazil1FNALKorea1 China1Pakistan1ASGC Croatia1Poland1GridKa Estonia1RALPortugal1PIC Finland1Russia1 federated France1IN2P3Spain1PIC Germany1 federatedGridKaSwitzerland1GridKa Greece1CNAFTaiwan1ASGC Hungary1CNAFUK4RAL India1ASGCUS8FNAL à Overall: >36 T2 sites, varying considerably in size n Computing model assumed nominal centres

GDB, 07/06/06 Evolving the Model à T1-T2 balance a function of location n US: Site connections well understood, capable T1 centre n Asia: Network situation evolving, plans mostly centred around ASGC T1 n Europe: Fragmented T1 resources, but excellent networking CMS T1s are often small fractions of highly capable centres à Consider a more ‘mesh’ like T1-T2 model in Europe n T2 centres connect to all T1 centres for data access Connect to an assigned T1 centre for MC output n Replicate ‘hot’ AOD/RECO across T1s according to T2 load n Advantages: Levels the load across the system, lowers peak load on a given T1 centre Could lower AOD disk requirements considerably n Issues: Places strong demands on T2 international connectivity Marginally increases the international data flow w.r.t. strict hierarchy

GDB, 07/06/06 Top-Down WAN Requirements à T1 centre dataflows (nominal T1): n T0 -> T1: 375TB of RAW/RECO in 100d LHC run: 1.5Gb/s Similar requirement outside running period n T1 T1 reproc AOD: 75TB AOD in 7d: 4Gb/s peak NB: very low duty cycle, 5% n T1 -> T2: 60TB typ. RECO/AOD in 20d to 5 centres: 3Gb/s T2 -> T1 is a much smaller dataflow, though reliability is important à For ‘meshed’ T1, add: n T1 T1 RECO replication: 30% of RECO within 7d?: 0.5Gb/s peak Assumes 30% replication for each re-proc pass, across T1s Low duty cycle - ‘In the shadow’ of the T1 T1 AOD requirement à T2 centre dataflows (nominal T2): n 60TB typ. In 20d: 0.6Gb/s n For ‘meshed’ centres, needs to be available to any T1 à NB: Safety factor of 2 on these bandwidths (as in CTDR)

GDB, 07/06/06 T2 Support Model à Support areas for T2 sites n Grid infrastructure / operational issues n CMS technical software / database / data management issues n Physics application support n Production operations and planning à For CMS issues, a ‘flat’ mutual support model is in place n T1/T2 sites receive and provide support within integration subproject n Technical software and application support from technical subproject New T2 sites ‘kickstarted’ with concentrated hands-on effort from experts n Model appears to scale so far; many sites taking part in SC4 tests. n Unclear that direct T1-T2 support is possible with very limited effort at T1 à Grid operational issues n We assume are handled through ROC system. n Good ongoing liaison will be needed to distinguish applications versus infrastructure issues - coming adoption of FTS will be a new test case

GDB, 07/06/06 Example: PhEDEx load test

GDB, 07/06/06 Moving Forward à Tier-2 site engagement n Large majority of Tier-2 sites are now active in setup/testing n Around 22/36 taking part in data transfer tests at some level n The mutual support model appears to be scaling so far à Network questions n network provision is not clear at every Tier-2 site In many cases, provision is requested but not yet firm n Work urgently with sites to resolve this and judge viability of a ‘mesh’ model n Work closely with LCG network group and others to determine best strategy for use of international networks OPN versus GEANT2 for T1-T2 international traffic? n Identify any network ‘holes’ rapidly and work to close them à Next few months will see substantial further progress n All CMS Tier-2 sites active, and involved in SC4 and/or CMS CSA2006 tests