Finding relevant datasets can be a time-consuming and challenging task, especially for self-describing file formats. Current solutions use either exact or partial keyword matching approaches to extract and process metadata queries, but they fail to capture semantic relationships between the metadata content and query keywords. To address this challenge, we introduce PSQS, a novel parallel semantic search method for self-describing files. The method leverages parallel processing and kv2vec semantic similarity measures to retrieve semantically relevant data efficiently. Our evaluation against existing metadata search solutions shows that PSQS offers a new, efficient and effective semantic search functionality for various fields where large self-describing files are used, such as scientific data management, leading to more accurate and efficient data retrieval.

Visualization aims to strengthen data exploration and analysis, especially for complex and high-dimensional data. High-performance computing (HPC) systems are typically large and complicated instruments that generate massive performance and operation time series. Monitoring HPC systems’ performance is a daunting task for HPC admins and researchers due to their dynamic natures. This work proposes a visual design using the bipartite graph’s idea to visualize HPC clusters’ structure, metrics, and job scheduling data. We built a web-based prototype, called JobViewer, that integrates advanced methods in visualization and human-computer interaction (HCI) to demonstrate the benefits of visualization in real-time monitoring HPC centers. We also showed real use cases and a user study to validate the efficiency and highlight the current approach’s drawbacks.

Detecting outliers is one of the fundamental tasks in visual analytics and valuable in many application domains, such as suspicious network cyberattack recognition. This paper introduces an approach to analyzing and visualizing high-dimensional time series, focusing on identifying multivariate observations that are significantly different from the others. We also propose a prototype, called MTSAD, to guide users when interactively exploring abnormalities in large time series. The prototype contains two views: the main window provides an overview of identified outliers overtime, the detail window investigates and explores the ranked temporal data entries based on their outlying contributions to the overall plots. The visual interface supports a full range of interactions, such as lensing, brushing and linking, ranking, and filtering. To validate the benefits and usefulness of our approach, we demonstrate MTSAD on real-world datasets of different numbers of attributes.

Fast growing "Big Data" demands present new challenges to the traditional distributed storage system solutions. In order to support cloud-scale data centers, new types of distributed storage systems are emerging. They are designed to scale to thousands of nodes, maintain petabytes of data and be highly reliable. The support for virtual machines is also becoming essential as it is one of the most important technology that supports cloud computing. To meet these needs, these distributed storage systems are implemented with advanced data distribution schemes. Data are striped and distributed across the storage cluster based on distribution algorithms instead of mapping tables. The existing algorithms usually balance the data distribution across nodes proportional to their capacity. However, they overlook distinct performance characteristics across different nodes and devices in the emerging heterogeneous storage environment. We propose a two-mode data distribution scheme in this study to maximize the overall performance and keep data balanced across the storage cluster at the same time. The working principle of the two-mode data distribution scheme is provided. We also present a new data read and write strategy to work with the two-mode scheme. We evaluate the computation time for data distribution using two-mode scheme and analyze its implication on the overall IO performance. We expect significant performance improvement while it still needs more analytical and experimental evaluation to further examine the details.

Object storage has been increasingly adopted in high-performance computing for scientific, big data applications. With object storage, applications usually use object IDs, queries, or collections to identify the data instead of using files. Since the object store changes the way data is accessed in applications, it introduces new challenges for I/O prediction, which used to work based on interfile or intrafile pattern detection. The key challenge is that the inputs of object-based applications are no longer expressed as static file names: they become much more dynamic and unstable, hidden inside application logic. Traditional prediction strategies do not work well in such conditions. In this paper, we introduce the use of provenance information, which was collected for data management in high-performance computing systems, in order to build an accurate coarse-grained (object-level) input prediction. The prediction results can be preloaded into a burst buffer to accelerate future reads. To our best knowledge, this study is the first to use provenance information in object stores to predict application inputs. Evaluation results confirm the effectiveness and accuracy of our provenance-based prediction and show that the proposed prediction system is feasible for real-work deployment.

Scientific workflow involves data generation, data analysis, and knowledge discovery. As the data volume exceeds a few terabytes (TB) in a single simulation run, the data movement, which happens among data generation, data analysis, and knowledge discovery, becomes a bottleneck in most scientific big data applications. Our previous work shows that reusing the analysis results can have a significant potential in reducing the overlap between data movement among compute nodes and storage nodes. In this work, we propose a new in-advance data analytics method to augment the result reuse. The fundamental idea of this in-advance data analytics method and its prototyping system is to predict the potential useful analytics operations by studying the users' analysis pattern. The predicted analysis operation is pro-actively performed on existing data and the analysis results are stored in an in-memory database for result reuse. The evaluation shows that the in-advance data analytics method and its prototyping system gains 1.2X-6.1X speedup in I/O performance improvement with 50% data overlapping and 10%-100% operation recommendation hit rate. The proposed in-advance data analytics method brings a new promising data reduction solution for big data applications.

Given the growing importance of supporting dataintensive sciences and big data applications, an effective HPC I/O solution has become a key issue and has attracted intensive attention in recent years. Active storage has been shown effective in reducing data movement and network traffic as a potential new I/O solution. Existing prototypes and systems, however, are primarily designed for read-intensive applications. In addition, they generally assume that offloaded processing kernels have small computational demands, which makes this solution a poor fit for data-intensive operations that have significant computational demands, including write-intensive operations. In this research, we propose a new Multilevel Active Storage (MAS) solution. The new MAS design can support and handle both read- and write-intensive operations, as well as complex operations that have considerable computational demands. Experimental tests have been carried out and confirmed that the MAS approach is feasible and outperformed existing approaches. The new multilevel active storage design has a potential to deliver a high performance I/O solution for big data applications in HPC.

Flash-memory based Solid State Drives (SSDs) embrace higher performance and lower power consumption compared to traditional storage devices (HDDs). These benefits are needed in HPC systems, especially with the growing demand of supporting Big Data applications. In this paper, we study placement and deployment strategies of SSDs in HPC systems to maximize the performance improvement, given a practical fixed hardware budget constraint. We propose a pattern-model approach to guide SSD deployment for HPC systems through two steps; characterizing workload and mapping deployment strategy. The first step is responsible for characterizing the access patterns of the workload and the second step contributes the actual deployment recommendation for Parallel File System (PFS) configuration combining with an analytical model. We have carried out initial experimental tests and the results confirmed that the proposed approach can guide placement of SSDs in HPC systems for accelerating data accesses. Our research will be helpful in guiding designs and developments for Big Data applications in current and projected HPC systems including exascale systems.

Many scientific applications nowadays generate a few terabytes (TB) of data in a single run and the data sizes are expected to reach petabytes (PB) in the near future. Enabling fast extraction of knowledge through analyzing these large datasets holds the key to faster scientific discoveries. However, reading data from traditional storage subsystem is a slow process as the I/O performance lags far behind computational performance. Reducing data movement from the storage subsystem is widely considered a viable option for improving performance of data analysis. In this paper, we propose Segmented Analysis, a data movement reduction strategy through reusing results, where multiple similar analysis tasks process the same segments of data. The basic idea is to segment the data accessed in an analysis task, to process the data segments with a given analysis task, and to store the results of segments in a cache for future use. In future, when an analysis task needs to perform the same process on the data segments for which the results are available in the cache, the task can avoid moving data and performing computation for the available results. The Segmented Analysis framework contains modules for computation and I/O access overlap detection, in situ segmentation, and segment result caching. We evaluate the Segmented Analysis strategy by varying factors like the overlap rate among analysis tasks, the request size and the granularity of segmentation. We observed 2X to 13X I/O and to 2X to 8X computation speedups when the overlap is above 50%.

Scientific I/O libraries, like PnetCDF, ADIOS, and HDF5, have been commonly used to facilitate the array-based scientific dataset processing. The underlying physical data layout information, however, is usually hidden from the upper layer's logical access. Such mismatching can lead to poor I/O. In this research, we have observed performance degradation in the case of concurrent sub-array accesses, where overlaps among calls that access sub-arrays led to high contention on storage servers due to the logical-physical mismatching. We propose a locality-driven high-level I/O aggregation approach to address these issues in this work. By designing a logical-physical mapping scheme, we try to utilize the scientific dataset's structured formats and the file systems' data distribution to resolve the mismatching issue. Therefore the I/O can be carried out in a locality-driven fashion. The proposed approach is effective and complements the existing I/O strategies, such as the independent I/O and collective I/O strategy. We have also carried out experimental tests and the results confirm the performance improvement compared to existing I/O strategies. The proposed locality-driven highlevel I/O aggregation approach holds a promise for efficiently processing scientific datasets, which is critical for the data intensive or big data computing era.