1. LHCbComputing Resources requests 2014-2017

2. 2 2014: changes since LHCb-PUB-2013-002 (March 2013) m Assume no further reprocessing of Run I data o (In LHCb-PUB-2013-002: full reprocessing in Summer 2014) m Introduction of disk at Tier 2 sites (T2-D) m Reduction by a factor two of simulated event size o Measured in Sim08 simulations o Due to better compression and removal of HepMC m Introduction of a disk replica of FULL.DST to facilitate restripping operations during 2014 and 2015 m Introduction of a (not replicated) ALL.DST stream o Contains complete DST information of events written to microDST o Facilitates re-generation of MDSTs as a way to encourage more analyses to move to the MDST format.

3. 2013-2014 CPU m CPU forecasts, usage, request m 2014 request was sized for usage forecast in March 2013 o Do not change request in current document m Justification: o Allows smooth ramp-up to Run 2 requirements o Retain possibility of reprocessing if compelling physics need 3

4. m Disk forecasts, usage, request m Current growth rate (simulation): 50 TB/week m Reduction in disk usage forecast due to o Reduction in MC event size (was 400kB, now 200kB) o No reprocessing at end 2014 m Move part of Tier1 request to Tier2 o Allows Tier2s to pledge independently o Tier1 countries should decide on most effective policy for allocating the total Tier1+Tier2 disk share 2013-2014 disk 4

5. 2013-2014 tape m Tape forecasts, usage, request m LHCb-PUB-2013-002 did not apply standard 85% efficiency correction o Now applied -> increase in request o 85% seems pessimistic for LHCb since most of our tape use is RAW + archive (i.e. written once, never deleted, no repacking needed) P Only lhcb-rdst tape class is eventually reused (FULL.DST) 5

6. Changes to computing model, 2015-2017 m See yesterday’s talk m Executive summary: o 12.5 kHz HLT rate P 10 (decreasing to 5) kHz Prompt P 0 (increasing to 5) kHz Parked P 2.5 kHz Turbo o Only prompt reconstruction, no reprocessing o Gradual reduction in CPU time for MC P Major developments required o Moore’s law still applies P Adapt software for more efficient vectorisation and multicore CPUs o Adjust parking rate and MC production to fit in (~constant budget) envelope of P 20%/year CPU growth P 15%/year disk growth P (25%/year tape growth not possible) 6

7. 2015-2017 7 m CPU o Fits in 20% growth envelope by: d 50% “parking” in 2017 d Postpone 2017 simulation to 2018 m Disk o Fits in 15% growth envelope m Tape o Tape growth is worrying d Largely incompressible (dominated by RAW data) d Need to find ways to finance it

8. Comparison with other experiments m CPU Disk m Tier0 m Tier1 m Tier2 m Tape o left T0 o right T1 8