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Worldwide event filter processing for calibration. Calorimeter Calibration Workshop Sander Klous September 2006. North Area ATLAS Detectors – Level 1 Trigger. ROB. ROB. ROB. ROB. PF. PF. Data Collection Network. PF. PF. SFI. SFI. SFI. L2PU. L2PU. Back End Network. L2PU. PF.
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Worldwide event filterprocessing for calibration Calorimeter Calibration Workshop Sander Klous September 2006
North Area ATLAS Detectors – Level 1 Trigger ROB ROB ROB ROB PF PF Data Collection Network PF PF SFI SFI SFI L2PU L2PU Back End Network L2PU PF L2PU PF SFOs Local Event Processing Farms mass storage Switch NORTH AREA Long existing idea: remote computing 2004 Copenhagen Edmonton Krakow Manchester Remote Event Processing Farms Packet Switched WAN: GEANT lightpath Bdlg. 513 The “Magni” Cluster • Bob Dobinson, Krzysztof Korcyl, Catalin Meirosu, John Renner-Hansen and Jim Pinfold, Richard Hughes-Jones
EF conc. Dataflow detail Remote farm
(Partial) Event Event (Partial) Event (Partial) Event Event LVL1 Info LVL1 Info LVL1 Info LVL1 Info LVL1 Info Ath / PESA RoutingTag RoutingTag RoutingTag RoutingTag RoutingTag StreamTag 1 StreamTag 2 StreamTag StreamTag 1 StreamTag 2 Ath / CALid PT Ath / CALIB Ath / CalStr PT Event LVL1 Info Stream n Stream 1 Stream 2 Remote StreamTag scenarios 2006 From LVL1 • ATL-DQ-ES-0076 • In preparation • See Sushkov presentation LVL2 SFO RoiB Ros/Robin pRos Stream selection Add to StreamTag1 EFD L2sv Input Create RoutingTag Routing DFM B ExtPT L2pu SFI (partially) build Routing Add to RoutingTag Create StreamTag D C Trash ExtPT Add to StreamTag2 Duplicating Output Output Stripping
EF conc. Remote farm Phase 1 Mass storage Combining the two concepts • Streaming/routing allows to prioritize the data • E.g. calibration events handled by remote farms No file I/O Bypass
Advantages of this approach Technical • Simpler, less problems with QoS of remote farms • Avoid processing bottleneck in Event Filter • Avoid File I/O bottleneck in SFOs (320 MB/s) • New bottleneck: network limitation, but… • Already network capacity exceeds local storage and processing • Network bandwidth grows much faster than I/O or CPU Organizational • Complies with policy of TDAQ and Streaming WG • Calibration events are allowed to be processed on remote farms • Calibration events are allowed to overlap with physics events
Use cases Online detector calibration • Access to offline compute power for online calibration • No compute power available in the pit • No space left to put extra compute power in the pit Testing of new and/or more complicated calibration triggers • Wild ideas can be tested in parallel to standard HLT operation • My personal favorite: Jet Energy Scale calibration with fully hadronic ttbar events (http://www.nikhef.nl/grid/trigger/calibration.php).
EF conc. Remote farm Phase 2 Phase 1 Mass storage Dreaming about a better future • Increasing the SFI event building rate