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 on large-scale distributed systems focuses on data management for extreme-scale systems. His other research interests include scalable performance analysis, bottleneck detection and tuning, and data management in distributed deep-learning workloads. Hariharan has worked at LLNL since 2021 and has received best paper awards at HPDC and CCGrid conferences.

Hariharan's current research focuses on workload-aware storage for HPC systems. He contributes to several projects within the laboratory, such as UnifyFS, the Scalable Checkpoint/Restart Library (SCR) project, FRACTALE, and GOTCHA. He is the task lead for I/O in the FRACTALE project, guiding research directions for data management for MD workflows, describing complex I/O patterns within the Flux scheduler, and improving utilization through data-aware job scheduling. These projects work towards a fundamental understanding of current and emerging needs for data management in HPC systems. 

Hariharan's expertise is not only recognized within his own research but also in the wider HPC community. He has made significant contributions as a reviewer for the storage track in many internationally recognized conferences and journals such as Supercomputing, Cluster, CCGrid, HPDC, IPDPS, and TPDS. His insights and critiques have helped shape the field. He has also been an active member of the organization committee for the Custer conference, holding roles such as Registration Chair and Web Chair.

Hariharan's academic journey is a testament to his dedication and passion for computer science. He received his Ph.D. in Computer Science in 2021 from the Illinois Institute of Technology, Chicago under the guidance of his advisor, Dr. Xian-He Sun. His academic journey began with a B.Tech in Computer Science and Engineering in 2013 from the National Institute of Technology, Jamshedpur India. After his undergrad, Hariharan gained practical experience as an application developer for Oracle Banking Platform in Mumbai, India.

Ph.D. Computer Science, Illinois Institute of Technology, Chicago

BTech Computer Science and Engg, National Institute of Technology, Jamshedpur, India

• 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.
• Izzet Yildirim, Hariharan Devarajan, Anthony Kougkas, Xian-He Sun, and Kathryn Mohror, “IOMax: Maximizing Out-of-Core I/O Analysis Performance on HPC Systems,” in Workshops of the International Conference on High Performance Computing, Network, Storage, and Analysis (SC-W 2023 in IPDPS’23), November 12–17, 2023, Denver, CO, USA
• 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.
• 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.
• 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.
• 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.
• 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.
• 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" In  Transactions on Storage (TOS), Vol 1, No 1, Article 1, 2020 (accepted and scheduled to appear). ACM, 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.
• 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
• 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
• 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).
• 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)
• 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

• 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.