CERN User Story


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CERN, the European Organization for Nuclear Research, is one of the world’s largest centres for scientific research. Its business is fundamental physics, finding out what the universe is made of and how it works. At CERN, accelerators such as the 27km Large Hadron Collider, are used to study the basic constituents of matter. This talk reviews the challenges to record and analyse the 25 Petabytes/year produced by the experiments and the investigations into how OpenStack could help to deliver a more agile computing infrastructure.

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  • Established by an international treaty at the end of 2nd world war as a place where scientists could work together for fundamental researchNuclear is part of the name but our world is particle physics
  • Our current understanding of the universe is incomplete. A theory, called the Standard Model, proposes particles and forces, many of which have been experimentally observed. However, there are open questions- Why do some particles have mass and others not ? The Higgs Boson is a theory but we need experimental evidence.Our theory of forces does not explain how Gravity worksCosmologists can only find 4% of the matter in the universe, we have lost the other 96%We should have 50% matter, 50% anti-matter… why is there an asymmetry (although it is a good thing that there is since the two anhialiate each other) ?When we go back through time 13 billion years towards the big bang, we move back through planets, stars, atoms, protons/electrons towards a soup like quark gluon plasma. What were the properties of this?
  • Biggest international scientific collaboration in the world, over 10,000 scientistsfrom 100 countriesAnnual Budget around 1.1 billion USDFunding for CERN, the laboratory, itselfcomesfrom the 20 member states, in ratio to the grossdomesticproduct… other countries contribute to experimentsincludingsubstantial US contribution towards the LHC experiments
  • The LHC is CERN’s largest accelerator. A 17 mile ring 100 meters underground where two beams of particles are sent in opposite directions and collided at the 4 experiments, Atlas, CMS, LHCb and ALICE. Lake Geneva and the airport are visible in the top to give a scale.
  • CERN is more than just the LHCCNGS neutrinos to Gran Sasso faster than the speed of light?CLOUD demonstrating impacts of cosmic rays on weather patternsAnti-hydrogen atoms contained for minutes in a magnetic vesselHowever, for those of you who have read Dan Brown’s Angels and Demons or seen the film, there are no maniacal monks with pounds of anti-matter running around the campus
  • LHC was conceived in the 1980s and construction was started in 2002 within the tunnel of a previous accelerator called LEP6,000 magnets lowered down 100m shafts weighing up to 35 tons each
  • The ring consists of two beam pipes, with a vacuum pressure 10 times lower than on the moon which contain the beams of protons accelerated to just below the speed of light. These go round 11,000 times per second being bent by the superconducting magnets cooled to 2K by liquid helium (-450F), colder than outer space. The beams themselves have a total energy similar to a high speed train so care needs to be taken to make sure they turn the corners correctly and don’t bump into the walls of the pipe.
  • - At 4 points around the ring, the beams are made to cross at points where detectors, the size of cathedrals and weighing up to 12,500 tonnes surround the pipe. These are like digital camera, but they take 100 mega pixel photos 40 million times a second. This produces up to 1 petabyte/s.
  • - Collisions can be visualised by the tracks left in the various parts of the detectors. With many collisions, the statistics allows particle identification such as mass and charge. This is a simple one…
  • To improve the statistics, we send round beams of multiple bunches, as they cross there are multiple collisions as 100 billion protons per bunch pass through each otherSoftware close by the detector and later offline in the computer centre then has to examine the tracks to understand the particles involved
  • To get Quark Gluon plasma, the material closest to the big bang, we also collide lead ions which is much more intensive… the temperatures reach 100,000 times that in the sun.
  • - We cannot record 1PB/s so there are hardware filters to remove uninteresting collisions such as those whose physics we understand already. The data is then sent to the CERN computer centre for recording via 10Gbit optical connections.
  • The Worldwide LHC Computing grid is used to record and analyse this data. The grid currently runs around 1 million jobs/day, less than 10% of the work is done at CERN. There is an agreed set of protocols for running jobs, data distribution and accounting between all the sites which co-operate in order to support the physicists across the globe.
  • So, to the Tier-0 computer centre at CERN… we are unusual in that we are public with our environment as there is no competitive advantage for us. We have thousands of visitors a year coming for tours and education and the computer center is a popular visit.The data centre has around 2.9MW of usable power looking after 12,000 servers.. In comparison, the accelerator uses 120MW, like a small town.With 64,000 disks, we have around 1,800 failing each year… this is much higher than the manufacturers’ MTBFs which is consistent with results from Google.Servers are mainly Intel processors, some AMD with dual core Xeon being the most common configuration.
  • CERN has around 10,000 physicist programmersApplications split into data recording, analysis and simulation.It is high throughput computing, not high performance computing… no parallel programs required as each collision is independent and can be farmed out using commodity networkingMajority of servers are running SL, some RHEL for Oracle databases
  • We purchase on an annuak cycle, replacing around ¼ of the servers. This purchasing is based on performance metrics such as cost per SpecInt or cost/GBGenerally, we are seeing dual core computer servers with Intel or AMD processors and bulk storage servers with 24 or 36 2TB disksThe operating system is Redhatlinux based distributon called Scientific Linux. We share the development and maintenance with Fermilab in Chicago. The choice of a Redhat based distribution comes from the need for stability across the grid, where keeping the 200 centres running compatible Linux distributions.
  • Get burnt in quickly, production and retire lateShort vs long programs can vary by up to 1 week
  • Generally running 30,000 jobs in the Tier-0 with up to 110,000 waiting to run, especially as conferences approach and physicists prepare the last minute analysis.
  • Our data storage system has to record and preserve 25PB/year with an expected lifetime of 20 years. Keeping the old data is required to get the maximum statistics for discoveries. At times, physicists will want to skim this data looking for new physics. Data rates are around 6GB/s average, with peaks of 25GB/s.
  • Around 60,000 tape mounts / week so the robots are kept busy
  • Our service consolidation environment is intended to allow rapid machine requests such as development servers through to full servers with live migration for productionCurrently based on Hyper-V and using SCVMM, we have around 1,600 guests running a mixture of Linux and Windows
  • Provides virtual machines to run physics jobs such that the users do not see any different between a physical machine and a virtual oneCurrently based on OpenNebula providing EC2 APIs for experiments to investigate using clouds
  • Can we find a model where Compute and Mass Storage reside on the same server?
  • Previous tests performed with OpenNebulaBottlenecks were identified within CERN’s toolchain (LDAP and batch system) rather than with the orchestrator
  • These are items which we foresee as being potentially interesting in a few months time where we would like to discuss with other users of openstack to understand potential solutions.
  • Infrastructure as a Service with a vibrant open source implementation such as OpenStack can offer efficiency and agility to IT services, both private and publicAs more users and companies move towards production usage, we need to balance the rapid evolution with the need for stabilityAs demonstrated by the World Wide Web’s evolution from a CERN project to a global presence, a set of core standards allows innovation & competition. Let’s not forget in our enthusaism to enhance OpenStack that there will be more and more sites facing the classic issues of production stability and maintenance.With the good information sharing amongst the community such as these conferences, these can be addressed.
  • Peaks of up to 25GBytes/s to handle with averages of 6 over the year.
  • CERN User Story

    1. 1. Towards An Agile Infrastructure at CERN<br />Tim Bell<br /><br />OpenStack Conference<br />6th October 2011<br />1<br />
    2. 2. What is CERN ?<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />2<br />ConseilEuropéen pour la RechercheNucléaire – aka European Laboratory for Particle Physics<br />Between Geneva and the Jura mountains, straddling the Swiss-French border<br />Founded in 1954 with an international treaty<br />Our business is fundamental physics and how our universe works<br />
    3. 3. OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />3<br />Answeringfundamental questions…<br /><ul><li>How to explainparticles have mass?</li></ul>We have theories but needexperimentalevidence<br /><ul><li>Whatis 96% of the universe made of ?</li></ul>Wecanonlysee 4% of itsestimated mass!<br /><ul><li>Whyisn’tthere anti-matterin the universe?</li></ul>Nature shouldbesymmetric…<br /><ul><li>Whatwas the state of matterjustafter the « Big Bang » ?</li></ul>Travelling back to the earliest instants of<br />the universewould help…<br />
    4. 4. Community collaboration on an international scale<br />Tim Bell, CERN<br />4<br />OpenStack Conference, Boston 2011<br />
    5. 5. The Large Hadron Collider<br />Tim Bell, CERN<br />5<br />OpenStack Conference, Boston 2011<br />
    6. 6. OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />6<br />
    7. 7. LHC construction<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />7<br />
    8. 8. The Large Hadron Collider (LHC) tunnel<br />8<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />
    9. 9. OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />9<br />
    10. 10. Accumulating events in 2009-2011<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />10<br />
    11. 11. OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />11<br />
    12. 12. Heavy Ion Collisions<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />12<br />
    13. 13. OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />13<br />
    14. 14. OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />14<br />Tier-0 (CERN):<br /><ul><li>Data recording
    15. 15. Initial data reconstruction
    16. 16. Data distribution</li></ul>Tier-1 (11 centres):<br /><ul><li>Permanent storage
    17. 17. Re-processing
    18. 18. Analysis</li></ul>Tier-2 (~200 centres):<br /><ul><li> Simulation
    19. 19. End-user analysis
    20. 20. Data is recorded at CERN and Tier-1s and analysed in the Worldwide LHC Computing Grid
    21. 21. In a normal day, the grid provides 100,000 CPU days executing 1 million jobs</li></li></ul><li>OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />15<br />Data Centre by Numbers<br />Hardware installation & retirement<br />~7,000 hardware movements/year; ~1,800 disk failures/year<br />
    22. 22. Our Environment<br />Our users<br />Experiments build on top of our infrastructure and services to deliver application frameworks for the 10,000 physicists<br />Our custom user applications split into<br />Raw data processing from the accelerator and export to the world wide LHC computing grid<br />Analysis of physics data<br />Simulation<br />We also have standard large organisation applications<br />Payroll, Web, Mail, HR, …<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />16<br />
    23. 23. Our Infrastructure<br />Hardware is generally based on commodity, white-box servers<br />Open tendering process based on SpecInt/CHF, CHF/Watt and GB/CHF<br />Compute nodes typically dual processor, 2GB per core<br />Bulk storage on 24x2TB disk storage-in-a-box with a RAID card<br />Vast majority of servers run Scientific Linux, developed by Fermilab and CERN, based on Redhat Enterprise<br />Focus is on stability in view of the number of centres on the WLCG<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />17<br />
    24. 24. Our Challenges – Compute<br />Optimise CPU resources<br />Maximise production lifetime of servers<br />Schedule interventions such as hardware repairs and OS patching<br />Match memory and core requirements per job<br />Reduce CPUs waiting idle for I/O<br />Conflicting software requirements<br />Different experiments want different libraries<br />Maintenance of old programs needs old OSes<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />18<br />
    25. 25. Our Challenges – variable demand<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />19<br />
    26. 26. Our Challenges - Data storage<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />20<br /><ul><li>25PB/year to record
    27. 27. >20 years retention
    28. 28. 6GB/s average
    29. 29. 25GB/s peaks</li></li></ul><li>OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />21<br />
    30. 30. Our Challenges – ‘minor’ other issues<br />Power<br />Living within a fixed envelope of 2.9MW available for computer centre<br />Cooling<br />Only 6kW/m2 without using water cooled racks (and no spare power) <br />Space<br />New capacity replaces old servers in same racks (as density is low)<br />Staff<br />CERN staff headcount is fixed<br />Budget<br />CERN IT budget reflects member states contributions<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />22<br />
    31. 31. Server Consolidation<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />23<br />
    32. 32. Batch Virtualisation<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />24<br />
    33. 33. Infrastructure as a Service Studies<br />CERN has been using virtualisation on a small scale since 2007<br />Server Consolidation with Microsoft System Centre VM manager and Hyper-V<br />Virtual batch compute farm using OpenNebula and Platform ISF on KVM<br />We are investigating moving to a cloud service provider model for infrastructure at CERN<br />Virtualisation consolidation across multiple sites<br />Bulk storage / Dropbox / …<br />Self-Service <br />Aims<br />Improve efficiency<br />Reduce operations effort<br />Ease remote data centre support<br />Enable cloud APIs<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />25<br />
    34. 34. OpenStack Infrastructure as a Service Studies<br />Current Focus<br />Converge the current virtualisation services into a single IaaS<br />Test Swift for bulk storage, compatibility with S3 tools and resilience on commodity hardware<br />Integrate OpenStack with CERN’s infrastructure such as LDAP and network databases<br />Status<br />Swift testbed (480TB) is being migrated to Diablo and expanded to 1PB with 10Ge networking<br />48 Hypervisors running RHEL/KVM/Nova under test<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />26<br />
    35. 35. Areas where we struggled<br />Networking configuration with Cactus<br />Trying out new Network-as-a-Service Quantum functions in Diablo<br />Redhat distribution base<br />RPMs not yet in EPEL but Grid Dynamics RPMs helped<br />Puppet manifests needed adapting and multiple sources from OpenStack and Puppetlabs<br />Currently only testing with KVM<br />We’ll try Hyper-V once Diablo/Hyper-V support is fully in place<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />27<br />
    36. 36. OpenStack investigations : next steps<br />Homogeneous servers for both storage and batch ?<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />28<br />
    37. 37. OpenStack investigations : next steps<br />Scale testing with CERN’s toolchains to install and schedule 16,000 VMs<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />29<br />Previous test results performed with OpenNebula<br />
    38. 38. OpenStack investigations : next steps<br />Investigate the commodity solutions for external volume storage<br />Ceph<br />Sheepdog<br />Gluster<br />...<br />Focus is on<br />Reducing performance impact of I/O with virtualisation<br />Enabling widespread use of live migration<br />Understanding the future storage classes and service definitions<br />Supporting remote data centre use cases<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />30<br />
    39. 39. Areas of interest looking forward<br />Nova and Glance<br />Scheduling VMs near to the data they need<br />Managing the queue of requests when “no credit card” and no resources<br />Orchestration of bare metal servers within OpenStack<br />Swift<br />High performance transfers through the proxies without encryption<br />Long term archiving for low power disks or tape<br />General<br />Filling in the missing functions such as billing, availability and performance monitoring<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />31<br />
    40. 40. Final Thoughts<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />32<br /><ul><li>A small project to share documents at CERN in the ‘90s created the massive phenomenon that is today’s world wide web
    41. 41. Open Source
    42. 42. Transparent governance
    43. 43. Basis for innovation and competition
    44. 44. Standard APIs where consensus
    45. 45. Stable production ready solutions
    46. 46. Vibrant eco-system
    47. 47. There is a strong need for a similar solution in the Infrastructure-as-a-Service space
    48. 48. The next year is going to be exciting for OpenStack as the project matures and faces the challenges of production deployments</li></li></ul><li>References<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />33<br />
    49. 49. Backup Slides<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />34<br />
    50. 50. CERN’s tools<br />The world’s most powerful accelerator: LHC<br />A 27 km long tunnel filled with high-tech instruments<br />Equipped with thousands of superconducting magnets<br />Accelerates particles to energies never before obtained<br />Produces particle collisions creating microscopic “big bangs”<br />Very large sophisticated detectors<br />Four experiments each the size of a cathedral<br />Hundred million measurement channels each<br />Data acquisition systems treating Petabytes per second<br />Top level computing to distribute and analyse the data<br />A Computing Grid linking ~200 computer centres around the globe<br />Sufficient computing power and storage to handle 25 Petabytes per year, making them available to thousands of physicists for analysis<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />35<br />
    51. 51. Other non-LHC experiments at CERN<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />36<br />
    52. 52. Superconducting magnets – October 2008<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />37<br />Afaulty connection between two superconducting magnets led to the release of a large amount of helium into the LHC tunnel and forced the machine to shut down for repairs<br />
    53. 53. CERN Computer Centre<br />Tim Bell, CERN<br />38<br />OpenStack Conference, Boston 2011<br />
    54. 54. Our Challenges – keeping up to date<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />39<br />
    55. 55. CPU capacity at CERN during ‘80s and ‘90s <br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />40<br />
    56. 56. Testbed Configuration for Nova / Swift<br />24 servers<br />Single server configuration for both compute and storage<br />Supermicro based systems<br />Intel Xeon CPU L5520 @ 2.27GHz<br />12GB memory<br />10Ge connectivity<br />IPMI<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />41<br />
    57. 57. Data Rates at Tier-0<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />42<br />Typical tier-0 bandwidth<br />Average in: 2 GB/s with peaks at 11.5 GB/s<br />Average out: 6 GB/s with peaks at 25 GB/s<br />
    58. 58. Web Site Activity<br />OpenStack Conference, Boston 2011<br />Tim Bell, CERN<br />43<br />
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