Hari Hariharan Devarajan profile

Hari Hariharan Devarajan

Computer Scientist

COMP / CASC DIV / Center for Applied Scientific Computing Division

Email

Biography

Hariharan Devarajan is a computer scientist in the Parallel Systems Group in the Center for Applied Scientific Computing (CASC) at Lawrence Livermore National Laboratory. His research focuses on data movement, storage systems, and performance analysis for large-scale scientific and super intelligence (SI) workflows. He works on explainable I/O, which connects low-level storage telemetry with workflow context to explain why I/O is slow; on provenance, which tracks the lineage and lifecycle of scientific data; and on targeted, workload-aware optimization of data movement on supercomputers. Hariharan has worked at LLNL since 2021 and has received best paper awards at HPDC and CCGrid, an R&D 100 Award for UnifyFS, and an LLNL Director's Institutional Award.

Hariharan is the principal investigator of Moirai, an LDRD project on trusted data provenance for HPC workflows, co-principal investigator of DLDL (deep learning data loading), and the data management thrust lead for the Heuretes strategic initiative on cross-site data movement. He previously led data management in the FRACTALE strategic initiative, where he built IFlux for intent-aware storage and scheduling in Flux. He created the DLIO Benchmark, which is part of the MLCommons MLPerf Storage suite, and DFTracer, a data-flow tracer used at LLNL, ALCF, and OLCF, and he leads development of the GOTCHA interposition library. His systematic study of the Rabbit software-defined storage system established its performance baseline on El Capitan-class systems.

Hariharan is active in the HPC community. He is Program Co-Chair of SSDBM 2026, Posters Co-Chair of HPDC 2026 and IEEE Cluster 2026, a review board member for IEEE Transactions on Parallel and Distributed Systems, and a program committee member for IPDPS, HPDC, Cluster, CCGrid, ICS, and ICPP. He gave the keynote at REX-IO 2026 and has served as a panelist at PACT 2026, HPDC 2026, and PDSW 2025. He mentors summer interns and serves as LLNL's technical point of contact for university research subcontracts.

He received his Ph.D. in Computer Science in 2021 from the Illinois Institute of Technology, Chicago, under the guidance of Dr. Xian-He Sun, and a B.Tech in Computer Science and Engineering in 2013 from the National Institute of Technology, Jamshedpur, India. Before graduate school, he was an application developer for the Oracle Banking Platform in Mumbai, India.

Education

  • Ph.D. Computer Science, Illinois Institute of Technology, Chicago
  • BTech Computer Science and Engg, National Institute of Technology, Jamshedpur, India

Publications

2026 10 publications

  • Hariharan Devarajan, Sarah Neuwirth, Chen Wang, Ray A. O. Sinurat, Neeraj Rajesh, Jay Lofstead, Vanessa Sochat, Daniel Milroy, and Thomas Scogland. "DataCrumbs: Efficient Cross-Layer Data Capture for Explainable I/O Performance in HPC Storage Stacks." Proceedings of the SC'26 Workshops of the International Conference for High Performance Computing, Networking, Storage and Analysis (SC Workshops'26): 8th Workshop on Programming and Performance Visualization Tools (ProTools'26), Chicago, IL, USA, IEEE, Nov. 2026.
  • Hariharan Devarajan, Ray A. O. Sinurat, Izzet Yildirim, Olga Kogiou, Aniruddha Marathe, and Nikoli Dryden. "ORION: Observability Framework for Hybrid Workflow-Centric I/O Monitoring in HPC Systems." Proceedings of the SC'26 Workshops of the International Conference for High Performance Computing, Networking, Storage and Analysis (SC Workshops'26): 8th Workshop on Programming and Performance Visualization Tools (ProTools'26), Chicago, IL, USA, IEEE, Nov. 2026.
  • Olga Kogiou, Hariharan Devarajan, Chen Wang, Weikuan Yu, and Kathryn Mohror. "iCR: Intent-Driven Adaptable Checkpoint/Restart." 2026 IEEE International Conference on Cluster Computing (CLUSTER'26), Alexandria, VA, USA, IEEE, Sep. 2026.
  • Karim Youssef, Hariharan Devarajan, Nikoli Dryden, and Roger Pearce. "WADO: A Distributed WORM Storage Service for Asynchronous Data Operations." Proceedings of the 38th International Conference on Scalable Scientific Data Management (SSDBM'26), ACM, Aug. 2026, pp. 1–12.
  • Ray A. O. Sinurat, Hariharan Devarajan, Nikoli Dryden, Haryadi S. Gunawi, and William Nixon. "HORATIO: Bridging Management and Analysis of Traces at Scale." Proceedings of the 38th International Conference on Scalable Scientific Data Management (SSDBM'26), ACM, Aug. 2026, pp. 1–12.
  • Ray A. O. Sinurat, William Nixon, Philip Carns, Huihuo Zheng, Sandeep Madireddy, Sam Foreman, Troy Arcomano, Robert B. Ross, Haryadi S. Gunawi, and Hariharan Devarajan. "GLANCED-IO: Taming I/O Optimization for Deep Learning at Scale." Proceedings of the 35th International Symposium on High-Performance Parallel and Distributed Computing (HPDC'26), ACM, Jul. 2026, pp. 305–318.
  • Karim Youssef, Sarah Neuwirth, Neeraj Rajesh, and Hariharan Devarajan. "Metis: Agentic Knowledge Synthesis for Explainable I/O Performance in HPC Systems." 6th Workshop on Re-envisioning Extreme-Scale I/O for Emerging Hybrid HPC Workloads (REX-IO'26), ACM, Jul. 2026.
  • Hariharan Devarajan, Vanessa Sochat, Daniel J. Milroy, and Tom Scogland. "IFlux: Intent-Aware Storage Tiers & Software Scheduling for HPC Systems." IEEE Transactions on Parallel and Distributed Systems, 2026, pp. 2236–2251.
  • Hariharan Devarajan, Brian Behlendorf, Blake Devcich, Dean Roehrich, Matt Richerson, Tony Floeder, Brent Petit, Don Boyd, Trace Hamada, Tim McCree, Gian-Carlo Defazio, James Corbett, Elsa Gonsiorowski, Cameron Stanavige, Nikoli Dryden, Roger Pearce, Kathryn Mohror, and Bronis R. de Supinski. "Chasing the Rabbit: A Systematic Exploration of Software-Defined HPC Storage." Proceedings of the 7th Workshop on Extreme-Scale Storage and Analysis (ESSA'26), held in conjunction with the 40th IEEE International Parallel and Distributed Processing Symposium (IPDPS'26), IEEE, May 2026.
  • Druva Dhakshinamoorthy, Ray A. O. Sinurat, Nikoli Dryden, Arnab K. Paul, and Hariharan Devarajan. "CoDL: A Framework for Studying Cross-Component Interference in Deep Learning Training Pipelines." 6th Workshop on Re-envisioning Extreme-Scale I/O for Emerging Hybrid HPC Workloads (REX-IO'26), ACM, Jul. 2026.

2025 6 publications

  • Chen Wang, Izzet Yildirim, Hariharan Devarajan, Kathryn Mohror, and Marc Snir. "Recorder: Comprehensive Parallel I/O Tracing and Analysis." arXiv:2501.04654, Jan. 2025.
  • Sarah Neuwirth, Hariharan Devarajan, Chen Wang, and Jay Lofstead. "XIO: Toward eXplainable I/O for HPC Systems." Proceedings of the 37th International Conference on Scalable Scientific Data Management (SSDBM'25), ACM, Jun. 2025, pp. 1–6.
  • Izzet Yildirim, Hariharan Devarajan, Anthony Kougkas, Xian-He Sun, and Kathryn Mohror. "WisIO: Automated I/O Bottleneck Detection with Multi-Perspective Views for HPC Workflows." Proceedings of the 39th ACM International Conference on Supercomputing (ICS'25), ACM, Jun. 2025, pp. 749–763.
  • Ian Lumsden, Stefano Markidis, Andong Hu, Ivy Bo Peng, Luca Pennati, Dewi Yokelson, Stephanie Brink, Olga Pearce, Tom Scogland, Hariharan Devarajan, Bronis R. de Supinski, Gian Luca Delzanno, and Michela Taufer. "Performance Optimization of an Exascale Implicit Kinetic Plasma Simulation on El Capitan." 2025 IEEE International Conference on eScience (eScience), IEEE, Sep. 2025, pp. 319–320.
  • Ian Lumsden, Hariharan Devarajan, Izzet Yildirim, Stefano Markidis, Andong Hu, Ivy Bo Peng, Luca Pennati, Dewi Yokelson, Stephanie Brink, Olga Pearce, Tom Scogland, Bronis R. de Supinski, Gian Luca Delzanno, Anthony Kougkas, Xian-He Sun, and Michela Taufer. "Optimizing I/O for an Exascale Implicit Kinetic Plasma Simulation using the Rabbit Storage System." 5th Workshop on Re-envisioning Extreme-Scale I/O for Emerging Hybrid HPC Workloads (REX-IO'25), 2025 IEEE International Conference on Cluster Computing Workshops (CLUSTER Workshops), IEEE, Sep. 2025, pp. 1–6. LLNL Director's Institutional Award.
  • Hammad Bin Ather, Chen Wang, Hariharan Devarajan, Hank Childs, and Kathryn Mohror. "SmartIO: A Lightweight End-to-End Workflow for Runtime I/O Optimization of HPC Systems." Proceedings of the Parallel Data Storage Workshop (PDSW'25), held in conjunction with SC25: The International Conference for High Performance Computing, Networking, Storage and Analysis, ACM, Nov. 2025, pp. 1396–1405.

2024 8 publications

  • Hariharan Devarajan,Adam Moody, Donglai Dai, Cameron Stanavige, Elsa Gonsiorowski, Marty McFadden, Olaf Faaland, Greg Kosinovsky, and Kathryn Mohror. "The impact of asynchronous I/O in checkpoint-restart workloads." In 2024, 5th Workshop on Extreme-Scale Storage and Analysis (ESSA). IEEE, 2024.
  • Ian Lumsden,Hariharan Devarajan,Jack Marquez, Stephanie Brink, David Boehme, Olga Pearce, Jae-Seung Yeom, and Michela Taufer. "Empirical Study of Molecular Dynamics Workflow Data Movement: DYAD vs. Traditional I/O Systems." In 2024, 23rd IEEE International Workshop on High Performance Computational Biology (HICOMB). IEEE, 2024.
  • Hariharan Devarajan, Gerd Heber, and Kathryn Mohror. "H5Intent: Autotuning HDF5 with User Intent." IEEE Transactions on Parallel and Distributed Systems, 2024.
  • Olga Kogiou, Hariharan Devarajan, Chen Wang, Weikuan Yu, and Kathryn Mohror. "Understanding Highly Configurable Storage for Diverse Workloads." 4th Workshop on Re-envisioning Extreme-Scale I/O for Emerging Hybrid HPC Workloads (REX-IO), IEEE, Sep. 2024.
  • Hariharan Devarajan, Ian Lumsden, Chen Wang, Konstantia Georgouli, Tom Scogland, Jae-Seung Yeom, and Michela Taufer. "DYAD: Locality-aware Data Management for accelerating Deep Learning Training." 2024 IEEE 36th International Symposium on Computer Architecture and High Performance Computing (SBAC-PAD), IEEE, Nov. 2024, pp. 13–24.
  • Hariharan Devarajan and Kathryn Mohror. "TailorFS: An Adaptive file system to support dynamic I/O requirements of HPC workloads." 2024 IEEE 36th International Symposium on Computer Architecture and High Performance Computing (SBAC-PAD), IEEE, Nov. 2024, pp. 81–92.
  • Hariharan Devarajan, Loic Pottier, Kaushik Velusamy, Huihuo Zheng, Izzet Yildirim, Olga Kogiou, Weikuan Yu, Anthony Kougkas, Xian-He Sun, Jae Seung Yeom, and Kathryn Mohror. "DFTracer: An Analysis-Friendly Data Flow Tracer for AI-Driven Workflows." SC24: International Conference for High Performance Computing, Networking, Storage and Analysis, Atlanta, GA, IEEE, Nov. 2024.
  • Yiheng Xu, Pranav Sivaraman, Hariharan Devarajan, Kathryn Mohror, and Abhinav Bhatele. "ML-based Modeling to Predict I/O Performance on Different Storage Sub-systems." 31st IEEE International Conference on High Performance Computing, Data, and Analytics (HiPC), IEEE, Dec. 2024.

2023 3 publications

  • Izzet Yildirim, Hariharan Devarajan, Anthony Kougkas, Xian-He Sun, and Kathryn Mohror. "IOMax: Maximizing Out-of-Core I/O Analysis Performance on HPC Systems." Workshops of the International Conference on High Performance Computing, Network, Storage, and Analysis (SC-W 2023), Denver, CO, USA, ACM, Nov. 2023, pp. 1209–1215.
  • Hariharan Devarajan and Kathryn Mohror. “Mimir: Extending I/O Interfaces to Express User Intent for Complex Workloads in HPC.” 2023 IEEE International Parallel and Distributed Processing Symposium (IPDPS) St. Petersburg, Florida: iEEE, May 2023.
  • Olga Kogiou, Hariharan Devarajan, Chen Wang, Weikuan Yu, and Kathryn Mohror. "I/O characterization and performance evaluation of large-scale storage architectures for heterogeneous workloads." 2023 IEEE International Conference on Cluster Computing Workshops (CLUSTER Workshops), IEEE, Oct. 2023, pp. 44–45.

2022 2 publications

  • Hariharan Devarajan and Kathryn Mohror. "Extracting and characterizing I/O behavior of HPC workloads". The 2022 IEEE International Conference on Cluster Computing (CLUSTER'22), September 6-9, 2022, Heidelberg, Germany.
  • Hariharan Devarajan, Anthony Kougkas, Huihuo Zheng, Venkatram Vishwanath, and Xian-He Sun, "Stimulus: Accelerate Data Management for Scientific AI applications in HPC," In the proceedings of the 2022 IEEE/ACM International Symposium in Cluster, Cloud, and Internet Computing (CCGrid'22), Taormina, Italy, May 16-19, 2022.

2021 2 publications

  • Jaime Cernuda Garcia, Hariharan Devarajan, Luke Logan, Keith Bateman, Neeraj Rajesh, Jie Ye, Anthony Kougkas, and Xian-He Sun.” HFlow: A Dynamic and Elastic Multi-Layered Data Forwarder”. The 2021 IEEE International Conference on Cluster Computing (CLUSTER'2021), IEEE Portland, OR.
  • Hariharan Devarajan,Huihuo Zheng, Anthony Kougkas, Xian-He Sun, and Venkatram Vishwanath. "DLIO: A Data-Centric Benchmark for Scientific Deep Learning Applications". In 2021 21st IEEE/ACM International Symposium on Cluster, Cloud and Internet Computing (CCGRID). IEEE. Best Paper.

2020 6 publications

  • Hariharan Devarajan,Anthony Kougkas, and Xian-He Sun. HReplica: A Dynamic Data Replication Engine with Adaptive Compression for Multi-Tiered Storage." 2020 IEEE International Conference on Big Data (Big Data), Atlanta, Georgia, USA, 2020.
  • Hariharan Devarajan,Anthony Kougkas, Keith Bateman, and Xian-He Sun. "HCL: Distributing Parallel Data Structures in Extreme Scales." In 2020 IEEE International Conference on Cluster Computing (CLUSTER). IEEE, 2020.

  • Anthony Kougkas, Hariharan Devarajan, and Xian-He Sun. "Bridging Storage Semantics using Data Labels and Asynchronous I/O." ACM Transactions on Storage (TOS), 2020.

  • Anthony Kougkas,Hariharan Devarajan, Keith Bateman, Jaime Cernuda, Neeraj Rajesh and Xian-He Sun. ChronoLog: A Distributed Shared Tiered Log Store with Time-based Data Ordering" Proceedings of the 36th International Conference on Massive Storage Systems and Technology (MSST 2020).
  • Hariharan Devarajan, Anthony Kougkas, Luke Logan, and Xian-He Sun. "HCompress: Hierarchical Data Compression for Multi-Tiered Storage Environments," 2020 IEEE International Parallel and Distributed Processing Symposium, New Orleans, Louisiana, USA.
  • Hariharan Devarajan, Anthony Kougkas, and Xian-He Sun. "HFetch: Hierarchical Data Prefetching for Scientific Workflows in Multi-Tiered Storage Environments," 2020 IEEE International Parallel and Distributed Processing Symposium (IPDPS), New Orleans, Louisiana, USA.

2019 2 publications

  • K. Feng,H. Devarajan,A. Kougkas, and X.-H. Sun. “NIOBE: An Intelligent I/O Bridging Engine for Complex and Distributed Workflows,” IEEE International Conference on Big Data, 2019
  • Anthony Kougkas, Hariharan Devarajan, and Xian-He Sun, "I/O Acceleration via Multi-Tiered Data Buffering and Prefetching", Journal of Computer Science and Technology, 2019

2018 2 publications

  • Hariharan Devarajan, Anthony Kougkas, Prajwal Challa, and Xian-He Sun. "Vidya: Performing Code-Block I/O Characterization for Data Access Optimization", In Proceedings of the IEEE International Conference on High Performance Computing, Data, and Analytics 2018.
  • Anthony Kougkas, Hariharan Devarajan, Xian-He Sun, and Jay Lofstead. "Harmonia: An Interference-Aware Dynamic I/O Scheduler for Shared Non-Volatile Burst Buffers", In Proceedings of the IEEE International Conference on Cluster Computing 2018 (Cluster'18)

Other 8 publications

  • Neeraj Rajesh, Hariharan Devarajan, Jaime Cernuda Garcia, Keith Bateman, Luke Logan, Jie Ye, Anthony Kougkas, and Xian-He Sun. “Apollo: An ML-assisted Real-Time Storage Resource Observer”. In Proceedings of the 30th International Symposium on High-Performance Parallel and Distributed Computing (HPDC '21). Association for Computing Machinery, New York, NY, USA, 147–159.
  • Anthony Kougkas, Hariharan Devarajan, Jay Lofstead, and Xian-He Sun. "LABIOS: A Distributed Label-Based I/O System", In Proceedings of the ACM 28th International Symposium on High-Performance Parallel and Distributed Computing (HPDC'19) Best Paper.
  • Hariharan Devarajan, Anthony Kougkas, and Xian-He Sun. "An Intelligent, Adaptive, and Flexible Data Compression Framework", In Proceedings of the IEEE/ACM International Symposium in Cluster, Cloud, and Grid Computing (CCGrid'19).
  • Anthony Kougkas, Hariharan Devarajan, and Xian-He Sun. "Hermes: A Heterogeneous-Aware Multi-Tiered Distributed I/O Buffering System", In Proceedings of the ACM 27th International Symposium on High-Performance Parallel and Distributed Computing (HPDC'18).
  • Anthony Kougkas, Hariharan Devarajan, and Xian-He Sun. "IRIS: I/O Redirection via Integrated Storage" (Slides), In Proceedings of the 32nd ACM International Conference on Supercomputing (ICS'18)
  • Anthony Kougkas, Hariharan Devarajan, and Xian-He Sun. "Enosis: Bridging the Semantic Gap between File-based and Object-based Data Models", In Proceedings of the ACM SIGHPC Datacloud'17, 8th International Workshop on Data-Intensive Computing in the Clouds.
  • Anthony Kougkas, Hariharan Devarajan, and Xian-He Sun. "Syndesis: Mapping Objects to Files for a Unified Data Access System", In Proceedings of the ACM SIGHPC MTAGS'17, 10th International Workshop on Many-Task Computing on Clouds, Grids, and Supercomputers, in conjunction with SC'17.
  • Hariharan Devarajan, Anthony Kougkas, Hsing-Bung Chen, and Xian-He Sun. "Open Ethernet Drive: Evolution of Energy-Efficient Storage Technology", In Proceedings of the ACM SIGHPC Datacloud'17, 8th International Workshop on Data-Intensive Computing in the Clouds in conjunction with SC'17

Awards

  • Outstanding service Award at Cluster 2021 for organizing the virtual platform and managing registrations for the conference.

  • Best Student Paper Award from the Computer Science Department at Illinois Tech 2021.

  • Best Paper Award at the 21st IEEE/ACM International Symposium on Cluster, Cloud and Internet Computing CCGrid (May'21)

  • Best Poster Nominee at the Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis 2019.

  • Karsten Schwan Best Paper Award at the 28th International ACM Symposium on High-Performance Parallel and Distributed Computing - HPDC (June'19)

  • Awarded “We Applaud Award” for designing a framework affecting the whole organization at Oracle Financial Services Software.

  • LLNL Director's Institutional Award for "Optimizing I/O for an Exascale Implicit Kinetic Plasma Simulation using the Rabbit Storage System" (iPIC3D on El Capitan).

  • R&D 100 Award for UnifyFS, 2024.

  • LDRD Strategic Initiative award: "FRACTALE: multi-cluster scheduling and data management" (Thrust Lead for Data Management), 2023.
  • Proposal award: "DLDL: Deep Learning Data Loading" (Co-Principal Investigator), 2025.
  • LDRD Exploratory Research award: "Trusted Data Provenance for HPC Workflows (Moirai)" (Principal Investigator, 27-ERD-025), 2026.
  • LDRD Strategic Initiative award: "Heuretes: cross-site data movement under time constraints" (Thrust Lead for Data Management), 2026.
Hari Hariharan Devarajan | People