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Large community of high-energy physicists share their data all around world making it necessary to ship a large number of files over wide- area networks. Regional disk caches such as the Southern California Petabyte Scale Cache have been deployed to reduce the data access latency. We observe that about 94% of the requested data volume were served from this cache, without remote transfers, between Sep. 2022 and July 2023. In this paper, we show the predictability of the resource utilization by exploring the trends of recent cache usage. The time series based prediction is made with a machine learning approach and the prediction errors are small relative to the variation in the input data. This work would help understanding the characteristics of the resource utilization and plan for additional deployments of caches in the future.

The Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC) distributes its data by leveraging a diverse array of National Research and Education Networks (NRENs), which CMS is forced to treat as an opaque resource. Consequently, CMS sees highly variable performance that already poses a challenge for operators coordinating the movement of petabytes around the globe. This kind of unpredictability, however, threatens CMS with a logistical nightmare as it barrels towards the High Luminosity LHC (HL-LHC) era in 2030, which is expected to produce roughly 0.5 exabytes of data per year. This paper explores one potential solution to this issue: software-defined networking (SDN). In particular, the prototypical interoperation of SENSE, an SDN product developed by the Energy Sciences Network, with Rucio, the data management software used by the LHC, is outlined. In addition, this paper presents the current progress in bringing these technologies together.

This work presents the design and implementation of an Open Storage System plugin for XRootD, utilizing Named Data Networking (NDN). This represents a significant step in integrating NDN, a prominent future Internet architecture, with the established data management systems within CMS. We show that this integration enables XRootD to access data in a location transparent manner, reducing the complexity of data management and retrieval. Our approach includes the creation of the NDNc software library, which bridges the existing NDN C++ library with the high-performance NDN-DPDK data-forwarding system. This paper outlines the design of the plugin and preliminary results of data transfer tests using both internal and external 100 Gbps testbed.

The efficiency of high energy physics workflows relies on the ability to rapidly transfer data among the sites where the data is processed and analyzed. The best data transfer tools should provide a simple and reliable solution for local, regional, national and in some cases intercontinental data transfers. This work outlines the results of data transfer tool tests using internal and external (simulated latency and packet loss) in 100 Gbps testbeds and compares the results among the existing solutions, while also treating the issue of tuning parameters and methods to help optimize the rates of transfers. Many tools have been developed to facilitate data transfers over wide area networks. However, few studies have shown the tools’ requirements, use cases, and reliability through comparative measurements. Here, we were evaluating a variety of high-performance data transfer tools used today in the LHC and other scientific communities, such as FDT, WDT, and NDN in different environments. Furthermore, this test was made to reproduce real-world data transfer examples to analyse each tool’s strengths and weaknesses, including the fault tolerance of the tools when we have packet loss. By comparing the tools in a controlled environment, we can shed light on the tool’s relative reliability and usability for academia and industry. Also, this work highlights the best tuning parameters for WAN and LAN transfers for maximum performance, in several cases.

Large community of high-energy physicists share their data all around world making it necessary to ship a large number of files over wide- area networks. Regional disk caches such as the Southern California Petabyte Scale Cache have been deployed to reduce the data access latency. We observe that about 94% of the requested data volume were served from this cache, without remote transfers, between Sep. 2022 and July 2023. In this paper, we show the predictability of the resource utilization by exploring the trends of recent cache usage. The time series based prediction is made with a machine learning approach and the prediction errors are small relative to the variation in the input data. This work would help understanding the characteristics of the resource utilization and plan for additional deployments of caches in the future.

Due to the increased demand of network traffic expected during the HL-LHC era, the T2 sites in the USA will be required to have 400Gbps of available bandwidth to their storage solution. With the above in mind we are pursuing a scale test of XRootD software when used to perform Third Party Copy transfers using the HTTP protocol. Our main objective is to understand the possible limitations in the software stack to achieve the target transfer rate; to that end we have set up a testbed of multiple XRootD servers in both UCSD and Caltech which are connected through a dedicated link capable of 400 Gbps end-to-end. Building upon our experience deploying containerized XRootD servers, we use Kubernetes to easily deploy and test different configurations of our testbed. In this work, we will present our experience doing these tests and the lessons learned.

The Large Hadron Collider (LHC) experiments distribute data by leveraging a diverse array of National Research and Education Networks (NRENs), where experiment data management systems treat networks as a “blackbox” resource. After the High Luminosity upgrade, the Compact Muon Solenoid (CMS) experiment alone will produce roughly 0.5 exabytes of data per year. NREN Networks are a critical part of the success of CMS and other LHC experiments. However, during data movement, NRENs are unaware of data priorities, importance, or need for quality of service, and this poses a challenge for operators to coordinate the movement of data and have predictable data flows across multi-domain networks. The overarching goal of SENSE (The Software-defined network for End-to-end Networked Science at Exascale) is to enable National Labs and universities to request and provision end-to-end intelligent network services for their application workflows leveraging SDN (Software-Defined Networking) capabilities. This work aims to allow LHC Experiments and Rucio, the data management software used by CMS Experiment, to allocate and prioritize certain data transfers over the wide area network. In this paper, we will present the current progress of the integration of SENSE, Multi-domain end-to-end SDN Orchestration with QoS (Quality of Service) capabilities, with Rucio, the data management software used by CMS Experiment.

A critical challenge of performing data transfers or remote reads is to be as fast and efficient as possible while, at the same time, keeping the usage of system resources as low as possible. Ideally, the software that manages these data transfers should be able to organize them so that one can have them run up to the hardware limits. Significant portions of LHC analysis use the same datasets, running over each file or dataset multiple times. By utilizing "ondemand" based regional caches, we can improve CPU Efficiency and reduce the wide area network usage. Speeding up user analysis and reducing network usage (and hiding latency from jobs by caching most essential files on demand) are significant challenges for HL-LHC, where the data volume increases to an exabyte level. In this paper, we will describe our journey and tests with the CMS XCache project (SoCal Cache), which will compare job performance and CPU efficiency using different storage solutions (Hadoop, Ceph, Local Disk, Named Data Networking). It will also provide insights into our tests over a wide area network and possible storage and network usage savings.