1. Remote Online Farms Sander Klous 01 11 010 001 1101 1110 11001 01011 110110 001101 1111111 0111000 11101010 01001110 110111001 000101101 1111010001 0101111100 111101001111 010110000101 H t W Z  0 On behalf of the Remote Online Farms Working Group ACAT 2007 25 April

2. 2 Large Hadron Collider and ATLAS

3. 3 Data processing nightmare There is no way to store all the info produced by ATLAS 40 million events per second x 1.5 MB/event = 60 TB per second In fact: 99.9995% of the data is thrown away - So… The data processing nightmare is all about storage Unfortunately… No Rigorous multilevel trigger system - First level in hardware - Higher levels in software But what if your favorite channel is not in the 0.0005%?

4. 4 Online bottleneck So… The data processing nightmare is all about CPU LVL1 HLT Scarce CPU resources Well, that’s a problem…

5. 5 Some are more equal than others… Detector calibration Physics selection Networking enables us to prioritize these activities So… The data processing nightmare is all about networking

6. 6 Amsterdam NIKHEF/SARA Data Acquisition 40 MHz Level 1 Level 2 Accept 1 in 500 Accept 1 in 50 Accept 1 in 10 Level 3 Computing grid Network switch Economics In fact, it is about balance Maximize performance  Minimize costs

7. 7 Gary Stix, editor of Scientific American Is it worth the effort? January 2001

8. 8 This can be difficult… The basics ROB Data Collection Network L2PU EF Event Filter North Area ATLAS Detectors Level 1 Trigger Back End Network SFO Mass storage Bdlg. 513 Copenhagen Edmonton Krakow Manchester Amsterdam RF Remote Event Processing Farms RF Packet Switched (GEANT) Switch lightpath Local Farm The “Magni” Cluster ROB SFI

9. 9 Input ExtPT Trash Output EFD B C D LVL2 RoiB L2sv L2pu Ros/RobinpRos DFM SFI (partially) build SFO Stream selection 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 Remote Stream implementation

10. 10 Grid/Proxy implementation SFI EFD Buffer PT Local PT Farm EFD Buffer PT Dispatcher Broker CE int.eu.grid HEP VO Infrastructure monitoring Application Monitoring Remote PTs Proxy PT Events HEP VO Database Worker Nodes UI Worker Nodes

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13. 13 Open issues Data management Software management Database access Authentication, Authorization and Accounting Performance and reliability Looking for PhD student… - If you are interested: Mail to sander@nikhef.nl

14. 14 Conclusion Remote online farms are interesting - From a physics perspective - From a computer science perspective - From an organizational perspective Infrastructure is put in place - Many open questions - More news next year PhD candidates: mail to sander@nikhef.nl