1. The ALICE DAQ: Current Status and Future Challenges P. VANDE VYVRE CERN-EP/AID

2. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 2 ALICE DAQ The original and updated requirements –The original requirements –The updated requirements: higher multiplicity, addition of detector Future challenges –The Region-Of-Interest readout –Online filtering –Enhanced data compression –The new architecture Current prototyping status –The ALICE DATE –Data transfer, Sub-event building and event building –Mass Storage System and Permanent Data Storage –The ALICE Data Challenge

3. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 3 ALICE DAQ The original and updated requirements –The original requirements –The updated requirements: higher multiplicity, addition of detector Future challenges –The Region-Of-Interest readout –Online filtering –Enhanced data compression –The new architecture Current prototyping status –The ALICE DATE –Data transfer, Sub-event building and event building –Mass Storage System and Permanent Data Storage –The ALICE Data Challenge

4. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 4 Original requirements: event size

5. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 5 Updated requirements: event size Higher multiplicity: increased TPC event size Transition Radiation Detector (TRD) added to ALICE Higher multiplicity: increased TPC event size Transition Radiation Detector (TRD) added to ALICE

6. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 6 Original requirements: data throughput Conservative data compression to reduce the data throughput to 1.25 GBytes/s.

7. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 7 Updated requirements: data throughput Conservative data compression and event rate reduction insufficient The TRD allows new types of online processing Conservative data compression and event rate reduction insufficient The TRD allows new types of online processing

8. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 8 ALICE DAQ The original and updated requirements –The original requirements –The updated requirements: higher multiplicity, addition of detector Future challenges –The Region-Of-Interest readout –Online filtering –Enhanced data compression –The new architecture Current prototyping status –The ALICE DATE –Data transfer, Sub-event building and event building –Mass Storage System and Permanent Data Storage –The ALICE Data Challenge

9. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 9 Future Challenges 1 For dielectron events –Region-Of-Interest identified by the TRD –Could be used for –Region-Of-Interest readout Electron tracks in the TPC and TRD detectors Target: Reduce the event size from 80 to 5 MBytes –Online Filtering Refine dielectron L1 trigger by a software filter Target: Reduce the event rate from 200 to 20 Hz Requires limited CPU power. Current estimate done with STAR data: 40 kCU Physics simulation and DAQ prototyping are starting

10. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 10 Future Challenges 2 For central and min. bias events Enhanced data compression for the TPC data Data compressed by applying to the raw data the following conversion: –Clusters finder –Local tracking –Raw data converted into: Parameters of a local track model Distances of the raw data clusters with the local track model Requires massive CPU power. Current estimate done with STAR data: 400 kCU

11. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 11 Updated requirements: data throughput Partial readout for dielectron triggers Online filtering Partial readout for dielectron triggers Online filtering

12. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 12 Architecture upgrade

13. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 13 ALICE DAQ The original and updated requirements –The original requirements –The updated requirements: higher multiplicity, addition of detector Future challenges –The Region-Of-Interest readout –Online filtering –Enhanced data compression –The new architecture Current prototyping status –The ALICE DATE –Data transfer, Sub-event building and event building –Mass Storage System and Permanent Data Storage –The ALICE Data Challenge

14. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 14 The ALICE DATE DATE: Data Acquisition and Test Environment Software framework for the ALICE DAQ development & prototyping Cover multiple needs with one common DAQ system –Need for a system to develop the DAQ –Need for a system for detector tests (lab and test beams) –Need for a framework to develop readout and monitoring programs ALICE DATE –Data flow: multiple LDCs, multiple GDCs –Run control, error reporting, bookeeping –Common software interfaces for readout, online monitoring with ROOT –Independent from physical layers: LDC I/O bus, event building network, GDC machine Used by ALICE test beams, NA57 and COMPASS

15. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 15 Data transfer Front-end electronics Detector Data Links DDL SIU DDL DIU RORC Source Interface Unit Destination Interface Unit Read Out Receiver Card Local Data Concentrator Front- End Digital Crate/Computer P2 Cavern P2 Access shaft Optical Fibre 200 meters LDC

16. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 16 Detector Data Link (DDL) One-to-one data communication link (FEE and DAQ) Main Requirements –Common interface between detector front-end electronics and DAQ Single hardware & software to develop and maintain Define interface soon to allow all the teams to work in parallel –Raw data transfer to DAQ –Data blocks download to FEE –Cover the distance from the detector in the cavern to the ALICE computing room in the access shaft (200 m.) Implementation –Optical link –Off-The-Shelf components Gbit/s opto-electronic –Prototypes integrated with DATE. –Tests with detectors will start this year

17. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 17 DDL SIU prototype

18. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 18 DDL DIU prototype

19. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 19 RORC prototype

20. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 20 Sub-event building Many-to-one data collection inside a crate or a computer –Collect data from several data sources over computer I/O bus –Assemble these data as one sub-event from a fraction of detector –Can work as a standalone DAQ system Data sources –Current data sources are electronics cards in VME or Camac –Current sub-event building done in software by a DATE program (Readout) running in on the processor in a VME board –In the future: data sources will be DDL links –First RORC prototypes done in VME form-factor (1 VME board) –Second RORC prototype will be in PCI form-factor (1 PC adapter) –Following closely the industry evolution (PCI, PCIX, NGIO, FIO, SIO)

21. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 21 Event building Event building network was initially a specially demanding application Today’s dominant trends in computing and networking industry: –Internet is the strongest incentive for always higher bandwidth –Commodity computing and networking is driving the industry –Switches replace shared media –Ethernet is the standard LAN media, TCP/IP is the standard protocol –Ethernet’s successors have the advantage of the existing installed base Event building network is similar to the backbone of a site like CERN: Ports: 15000 on Eth10, 2000 sur Eth 100, 30 on Eth 1000, Switches: 100 Eth100 or Eth1000, central bw 60 Gbps Work focus: can we use standard LAN media and protocol and how ?

22. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 22 Mass Storage System Network MSS core server MSS Meta data ALICE DAQ Tape Arrays Disk Arrays Main Data Servers GDC Secondary Data Servers NFS Servers DFS Servers Client System Client System

23. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 23 Mass Storage System –Isolate the DAQ and computing architecture from the problems of physical data recording, CDR, volume handling etc the technology evolution in the storage area (magnetic/optical, robotic etc) –Provide a logical structure to the storage infrastructure For example a file system: /hpss/alice/2005/pbpb_run/run00001.raw /hpss/alice/2005/pbpb_run/run00002.raw... –The MSS currently used by ALICE is HPSS but HPSS expensive and supported on a limited set of platforms, but MSS market is small –Other systems used in future prototypes: CASTOR, EUROSTORE

24. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 24 Permanent Data Storage Multiple parallel streams of magnetic tapes –By LHC startup: Standard drive should achieve 30-50 MBytes/s Standard capacity should be 100-200 GBytes 40 drives with 80 (dis)mounts/hour in total Current CERN installation –Drive bandwidth 10 MBytes/s –Tape capacity 50 GBytes –45 drives –6 silos of 6000 cartridges of 50 GB: 1.8 PBytes capacity Feasible but expensive solution. Ratio disk storage cost/tape storage cost decreasing rapidly By LHC time, online disk storage and offline archiving could be cost effective

25. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 25 Prototyping Development and prototyping progressing in parallel Prototyping with the ALICE Data Challenge (ADC) –Combined activity of the ALICE DAQ/ALICE Offline/IT teams –ADC1: 6 days at 14 MB/s (7 TB ROOT dataset) ADC2: Large DATE system –Data sources (18 LDCs) 9 Motorola VME + 2 IBM WS (Test beam area - Hall 887 on Prevessin site) 7 Motorola VME + DDL prototypes (DAQ Lab - Bld 53 on Meyrin site) –Network: Fast Ethernet switches, gigabit ethernet backbone –Data destinations ( computing center) 20 PC/Linux for event building, ROOT I/O formatting, L3 filter Central data recording (Target 100 MB/s)

26. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 26 ALICE Data Challenge II

27. P. Vande Vyvre CERN/EP The ALICE DAQ : Current Status and Future Challenges 07-Feb-2000 27 Conclusion The requirements of the ALICE DAQ have evolved a lot New ways to reduce the huge data volume will be investigated –Region-Of-Interest readout –Online filtering –Enhanced data compression scheme Development progressing (almost according to schedule) The prototypes are tested during the ALICE Data Challenges Future milestones: –Integration of DDL with detectors –ALICE Data Challenge II: from DDL to MSS @ 100MB/s Computing and communication technology evolution positive Area of concerns: Storage cost and Mass Storage System