1. Worldwide event filter processing for calibration Calorimeter Calibration Workshop Sander Klous September 2006

2. 2 Long existing idea: remote computing 2004 ROB L2PU SFI PF Local Event Processing Farms Data Collection Network North Area ATLAS Detectors – Level 1 Trigger Back End Network SFOs mass storage NORTH AREA Bdlg. 513 Copenhagen Edmonton Krakow Manchester PF Remote Event Processing Farms PF Packet Switched WAN: GEANT Switch lightpath PF The “Magni” Cluster Bob Dobinson, Krzysztof Korcyl, Catalin Meirosu, John Renner-Hansen and Jim Pinfold, Richard Hughes-Jones

3. 3 Dataflow detail Remote farm EF conc.

4. 4 Input ExtPT Trash Output EFD B C D LVL2 RoiB L2sv L2pu Ros/RobinpRos DFM SFI (partially) build SFO Stream selection StreamTag scenarios 2006 Stream n Stream 1Stream 2 Ath / CALid Ath / PESA PT From LVL1 Event LVL1 Info Add to StreamTag1 Stripping Ath / CalStr Ath / CALIB PT Add to RoutingTag Create RoutingTag Routing Duplicating Routing (Partial) Event LVL1 Info RoutingTag StreamTag 1 Event LVL1 Info RoutingTag StreamTag 2 Event LVL1 Info RoutingTag StreamTag 2 (Partial) Event LVL1 Info RoutingTag StreamTag (Partial) Event LVL1 Info RoutingTag StreamTag 1 Add to StreamTag2 Create StreamTag ATL-DQ-ES-0076  In preparation  See Sushkov presentation Remote

5. 5 Combining the two concepts Streaming/routing allows to prioritize the data  E.g. calibration events handled by remote farms Phase 1 Remote farm EF conc. Mass storage Bypass No file I/O

6. 6 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

7. 7 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). http://www.nikhef.nl/grid/trigger/calibration.php

8. 8 Dreaming about a better future Increasing the SFI event building rate Phase 1 Phase 2 Remote farm EF conc. Mass storage