1. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni Genève, January 17, 2001

2. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni 2001 Farm for LHCb-Italy

3. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni Components (Motherboards, Racks, NAS, Switches)

4. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni 2001 Funded Investments Funded racks (with cooling and power supply)16 ML Asus FX monoprocessor motherboards: on-board network IF Intel Pentium III 800 MHz CPU 256 MB RAM 133 MHz bus 1530 ML NAS RAID Raidzone OpenNAS RS15-R1200 Dual processor Pentium III 800 MHz 15 IDE 80 GB Ultra ATA/100 disks Dual 100 Mbps network IF Dual redundant 300W hot swap power supply 160 ML 56 ports ethernet switch16.5 ML Total102.5 ML

5. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni 2001 Investments Availability of more funds, later in 2001, is conditional to: The production of a believable computing model for 2001 (given the present WAN bandwidth). The evidence of a high load of the installed CPUs. The use of produced MC by Italian institutes for their own analyses. All LHCb Italian groups are therefore invited to estimate their CPU need for MC production in 2001, in order to ask more funds.

6. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni Preliminary Farm Tests Performed in Bologna Network boot  Boot-prom required (PXE?) Swap-less operation  Memory requirements for job execution nodes is stable RAM errors  Memtest86 and badram NFS functionalities  Kernel 2.2.18 required in order to allow broken setuid on NFS root Network boot for Asus FX boards Wake on network In order to switch on and off boards from remote. Electromagnetic interferences between neighbouring boards

7. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni Finale Computing Organization MONARC hierarchy Tier-0: CERN Tier-1: Regional Centre (1 for each country). Tier-2: Satellites of Tier-1 (mainly devoted to analysis). Tier-3: Department Server (1 for each institute). Tier-4: Desktop Data formats RAW, RAWmc ESD, ESDmc: Event Summary Data; reconstruction output. AOD: Analysis Object Data, public analysis format. DPD: Derived Physics Data, private analysis format, ntuples.

8. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni LHCb Differences With Respect to Other LHC Experiments The first stage in the analysis (ESD  AOD, final state reconstruction) is performed in common for all the analyses that subsequently follow (more than one algorithm could have to be run on any single event, if that event satisfies more than one tag criterion). The first stage in the analysis is therefore performed in production (Production Analysis) soon after data taking at CERN (real data) and in MC production centres (MC). AOD (20 TB/a real data) are systematically distributed to all Tier-1 centres. ESD (100 TB/a real data) are kept in production centres. Other LHC experiments export ESD.

9. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni Final Tier-n Organization in Italy ATLAS plan Tier-1 stores ESD. Performs reprocessing and first analysis stage (AOD production). No MC production. Tier-2s store AOD and perform MC production + analysis. Tier-3s execute analysis CMS plan Tier-1 stores ESD and performs collaboration scheduled MC production + reprocessing Tier-2++ (Legnaro) performs local requested MC production + reprocessing + analysis Tier-2s/Tier-3s produce local requested MC production + analysis Tier-2/Tier-3 difference is not functional

10. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni LHCb Computing Model Tasks MC production (  RAWmc,  ESDmc), production analysis (ESDmc  AOD) and reprocessing, performed in Tier-1 (but also in Tier-3 dead time). User analysis (AOD  DPD) performed in a collaboration between Tier-1 (selection) and Tier-3 (computation). Interactive analysis of DPD performed in Tier-3 and Tier-4. Storage RAW and ESD stored only in the Tier-0 (CERN) (not distributed). RAWmc and ESDmc stored only in the Tier-1 centre which produce them (not distributed). AOD (from real data and all Tier-1 MC) stored in every Tier­1 (distributed). DPD (ntuples) stored in Tier-3.

11. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni LHCb Tier-n Tasks Tier-1 MC production (  RAWmc,  ESDmc) + production analysis (  AOD) + reprocessing. User analysis (  DPD) in collaboration with Tier-3s. Storage of RAWmc and ESDmc produced in the centre itself. Storage of all the AOD (real data produced at CERN, MC data produced in all Tier-1 centres). Tier-3s User analysis (  DPD) in collaboration with Tier-1. DPD storage. Interactive analysis of DPD. In dead time, MC production. Tier-2s (not in the MONARC sense) are large Tier-3, functionally equivalent to Tier-3.

12. Computing for LHCb-Italy Domenico Galli, Umberto Marconi and Vincenzo Vagnoni 2007 LHCb Tier-n Organization in Italy 1 Tier-1 centre: 140 kSI95, 110 TB disk. 9 Tier-3 centres (Bologna, Cagliari, Ferrara, Firenze, Frascati, Genova, Milano, Roma1, Roma2): average 1 kSI95, 1 TB disk. Tier-3 dimension can vary on the basis of group size and analysis activity. Large Tier-3 centres could be named Tier-2, but not in the MONARC meaning.