CERN les.robertson@cern.ch december-00 La Politique du tout PC au CERN Séminaire EDF Clamart – 15...

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CERN les.robertson@cern.ch december-00 La Politique du tout PC au CERN Sminaire EDF Clamart 15 dcembre 2000 Les Robertson CERN/IT Genve Slide 2 CERN december-00 - #2les robertson - cern/it Sommaire Le problme La stratgie Les difficults Slide 3 CERN les.robertson@cern.ch december-00 Le problme Slide 4 CERN december-00 - #4les robertson - cern/it Architectures & operating systems supported at end 1999 AIX Windows NT Irix Solaris Digital Unix HP-UX MAC-OS Linux Windows 95 SPARC MIPS Intel IA-32 PA-RISC Power PC Alpha Windows 2000 The legacy of ten years of RISC computing Slide 5 CERN december-00 - #5les robertson - cern/it Combien darchitectures et systmes dexploitation sont vraiment ncessaire? Combien cote le support? Combien vaut la diversit? Comment imposer des limitations de choix dans un environnement de recherche scientifique ? Slide 6 LOrganisation Europenne pour la Recherche Nuclaire 20 pays europens 2,700 employes 6,000 utilisateurs CERN Slide 7 december-00 - #7les robertson - cern/it The Large Hadron Collider - LHC LHC accelerator under construction Proton-proton collider 27 km of super-conducting magnets Target date for first beams - 2005 Four experiments Example - CMS 2000 physicists, 150 universities Slide 8 The LHC Detectors CMS ATLAS LHCb 3.5 PetaBytes / year ~10 8 events/year Slide 9 CERN december-00 - #9les robertson - cern/it HEP Computing Characteristics Large numbers of independent events trivial parallelism Large data sets smallish records mostly read-only Modest I/O rates few MB/sec per fast processor Modest floating point requirement SPECint performance High Througput Computing Very large aggregate requirements computation, data Scaling up is not just big it is also complex and once you exceed the capabilities of a single geographical installation ? Slide 10 network servers tape servers disk servers application servers Generic computing farm Cern/it/pdp-les.robertson 10-98-10 les.robertson@cern.ch Slide 11 ~10K SI95 1200 processors Non-LHC Moores Law estimate of the capacity for fixed level of investment, fixed number of processors LHC 10-20K cpus? Slide 12 network servers tape servers disk servers application servers Generic computing farm Cern/it/pdp-les.robertson 10-98-12 les.robertson@cern.ch LHC physics facility 4 experiments 2 M SPECint95 10-20K processors 2 PByte disk >20 K disks Slide 13 CERN december-00 - #13les robertson - cern/it Summary of the problem HEP is using far too many operating systems in many cases with only slightly different functionality or hardware cost benefits and at a high cost for users and support teams The scale of LHC computing - massive numbers of processors/boxes integration of regional computing centres and CERN problem is how to manage on this scale while limiting costs of equipment, management & support We must reduce the diversity while retaining flexibility to use low-cost, mass market components and adapt rapidly to changing physics needs Slide 14 CERN les.robertson@cern.ch december-00 La stratgie Slide 15 CERN december-00 - #15les robertson - cern/it Opportunity PCs + { Linux Windows } offer an historic opportunity to reduce the solution set Costs and performance PCs will consistently be among the very best price/performers for HEP codes They may not be the fastest,but they are fast enough Linux -a non-proprietary operating system compatible with the recent Unix history Windows a mass market alternative widely used on the desktop Slide 16 CERN december-00 - #16les robertson - cern/it Policy Restrict ourselves to PC hardware with Linux or Windows 2000 Develop a migration plan - progressively freeze support for other Unixes, announcing end-dates which are reasonable for old experiments, strongly discourage further investments in RISC systems by current and future experiments install large Linux public facility, testbed for future experiments Concentrate investment in Linux and Windows bring support up to the standards of proprietary Unixes tackle the problems of scaling the management and performance of physics farms and desktops seek HEP-wide consensus Slide 17 CERN december-00 - #17les robertson - cern/it But do not be unrealistic ---- This is a convergence policy which looks realistic now and will provide a single starting point for LHC computing but we can be sure that the industry will not stand still, and we shall sooner or later have to expand the systems and architectures supported AIX WNT Irix Solaris Digital Unix HP-UX MAC-OS Linux Windows 95 SPARC MIPS Intel IA-32 PA-RISC Power PC Alpha Linux Windows 2000 Intel IA-64 - - - ? Slide 18 CERN les.robertson@cern.ch december-00 Les difficults et l'tat de la migration Slide 19 CERN december-00 - #19les robertson - cern/it Difficulties - I Physics (almost) entirely Unix based Linux is not quite ready (Too) wide a choice of kernels, compilers, debuggers Different versions supported by different applications Some applications not supported on Linux Complex packages (Oracle, AFS) better go with the standard platform Stability problems under load Who provides in-depth, on-site Linux systems support? Solution: Standard Linux Package certified for all CERN applications Solaris/SPARC for special purposes Open posts for Linux experts Slide 20 CERN december-00 - #20les robertson - cern/it Difficulties - II In a research environment Easy to estimate the costs of systems support Hard to estimate the cost of application migration The application experts have already moved on The developers have other (more interesting) problems to solve The problem is not only to port the code but (more important) to acquire confidence in the physics results Compiler, architecture, old bugs But there are signs that Linux+Intel are as good as any! In the past, the production use of multiple architectures was an important factor in finding bugs Slide 21 CERN december-00 - #21les robertson - cern/it Current Status Physics For older experiments Strong resistance to aggressive migration proposal Agreement for complete freeze on all proprietary Unixes during 2003 For future experiments (not yet collecting data) General agreement on Linux/Intel for production, but require a second (limited) development platform for validation For new experiments collecting data now Easy to calculate the benefits Have already completed migration Slide 22 CERN december-00 - #22les robertson - cern/it Current Status other applications Desktop applications Web, Office, . Windows 2000 Engineering applications Aggressive migration plan to Windows NT/2000 & Linux, with some residual SUN Major exception is mechanical CAE (Euclid + Digital Unix) Administration Database (Oracle) on SUN Clients Web-based (Outlook/Netscape) Strong pockets of MAC resistance led by the Directorate Slide 23 CERN december-00 - #23les robertson - cern/it Conclusions Les besoins normes du LHC exigent la standardisation et lutilisation des composants bon-march Opportunit Linux + Windows 2000 avec Intel IA32/64 & Ethernet Grande inertie (rsistance?) de la part des vielles expriences - il faudra 4 annes pour terminer la migration Mais dj plus de trois quarts des systmes installs et 90% de la capacit sont Linux/Intel