Data requirements for the SKA - CIRA

Data requirements for the SKA - CIRA

Australian SKA Pathfinder - ASKAP• 36 antennas with Phased Array Feeds(field of view 30 deg 2 ).• Total output data rate per antenna =0.6Tbps.• Connecting antennas to the central sitebeamformer and correlator requires Tbpsdata pipelines over distances up to 6 km.• 20 Gbps data flow from correlator to centralprocessor (100s of km).• Data processing load ~2 Pflop/s at MRO andup to 1 Pflop/s at Pawsey Centre.• Calibration, imaging, catalogue productionare all automatic.CSIRO. Lisa Harvey-Smith

Australian SKA Pathfinder - ASKAP

Possible Architecture for SKAFigure: Paul AlexanderCSIRO. Lisa Harvey-Smith

SKA Data Rates to the CorrelatorTable: Paul AlexanderCSIRO. Lisa Harvey-Smith

SKA Correlator Strawman (SKA Memo 126)• SKA Correlator will require 1 Exaflop/s of processing and consume 1 TeraWatt ofpower.• Future lies in FGPAs/ASIC/GPUs for faster, cheaper correlators.• Processing power per Watt up to 30 x cheaper for parallel implementation (C.J. Harris,UWA BSc Thesis).CSIRO. Lisa Harvey-SmithASIC = Application Specific Integrated Circuit

Are these processing rates possible?SKACSIRO. Lisa Harvey-Smith

SKA Data Transport• Data transport currentlyexpensive over long distances(amplification every 80km,regeneration every 600km).• Limited bit rate limits sciencecapability of telescope.• Trenching/Cabling dominate cost– NBN may provide existinginfrastructure in Australia.• One solution: beamform remotedishes in stations beforetransporting signals.• Other innovative solutions mayemerge.Basic cost-scaling for long baselines (McCool SKA Memo 119).CSIRO. Lisa Harvey-Smith

SKA Data Products• Estimated volume of fully processed data range from 10-100 PB perhour (Tim Cornwell).• That is 1.2 exabytes of data per day.• Astronomers will interact with data products entirely through a VO.• Future research will involve mining images, catalogues. NOT reducingdata.• This type of post-processing (e.g. comparing multi-wavelengthcatalogues from different telescopes) may require as much computingeffort as the initial generation of the data!CSIRO. Lisa Harvey-Smith

Data Challenges: Aperture Arrays for SKASKA will rely on large numbers of phased arrays to achieve wide fieldof-viewfor fast survey capability.• For single-pixel feeds, FoV set by dish size.• For Phased Array Feeds , FOV set by dish size times number ofreceptor elements per dish.• For Aperture Arrays, FoV set by signal processing power.• Science surveys will have to consider trade-offs to stay within cost.CSIRO. Lisa Harvey-Smith

Data Processing challenges: Pulsar Science• Pulsar searching and timing one of the key science areas for SKA.• For pulsar searching, need to process each pixel individually.• For pulsar surveys, most of collecting area concentrated in central 1- 5 km to avoid gatheringdata that is impossible to process.• Data rate from SKA pulsar survey is 0.5 Tbps (Smits, SKA Memo 105).• Required computational power for a deep real time analysis is 12 Pflop/s (Smits, SKA Memo105).ᅠ2PP ᅠ L baseline-D 2 dishN FOV• For receptor arrays, the survey can be performed faster, but the computational requirementsand data rates will go up.• Search for fast radio transients also data intensive. Commensal Real-Time ASKAP FastTransient Search (CRAFT) will develop techniques for SKA fast transient searching.CSIRO. Lisa Harvey-Smith

Possible Solutions• Some flexibility is on offer here e.g. search for millisecond pulsars coulduse only the baselines < 1km, fewer beams formed.• Can reduce processing load by generating redundancy on short baselinesusing a regular grid in central core (Bunton 2010 IEEE in prep).• Perform targeted searches for millisecond pulsars towardsLMC/SMC/Globular Clusters/Supernova Remnants (SKA Phase 1).CSIRO. Lisa Harvey-Smith

Summary of challenges• SKA is achievable but unleashing its full potential is expensive.• Data transport over long baselines is costly, but innovative solutions will emerge.• SKA’s Pawsey HPC centre will generate ~1 Exabyte of data per year and require100MW of power.• SKA performance may be power limited!• CSIRO have $47M funding for solar power for ASKAP (1 MW) and geothermalcooling for the supercomputer.• Development of renewable energy sources will be important to avoid prohibitivepower costs.CSIRO. Lisa Harvey-Smith

Thank youCSIRO Astronomy & Space ScienceContact UsLisa Harvey-SmithCSIRO SKA Project ScientistPhone: 1300 363 400 or +61 3 9545 2176Email: Web: www.csiro.auCSIRO. Lisa Harvey-Smith

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