XRootD and FTS Workshop @ CNRS Rhône Auvergne Delegation Lyon, France

Sep 14, 2026, 9:00 AM → Sep 18, 2026, 6:00 PM Europe/Paris

Amphitheatre (CNRS Delegation Rhône-Auvergne)

Andrew Bohdan Hanushevsky (SLAC National Accelerator Laboratory (US)), Guilherme Amadio (CERN), Mihai Patrascoiu (CERN), Luca Mascetti (CERN), Maria Arsuaga Rios (CERN), Jean-Yves NIEF (CC-IN2P3)

LOGIN to see the Zoom connection details. :)

The 2026 XRootD and FTS workshop will take place on 14-18 September, 2026, at CNRS Rhône Auvergne Delegation Amphitheater located in Lyon, France. This event will be hosted by CC-IN2P3.

The XRootD and FTS workshop brings together the XRootD and FTS developers and people from Academia, Research, and Industry to discuss current and future data access activities as related to the XRootD framework and to the FTS project. 

Presentations focus on achievements, shortcomings, requirements and future plans for both XRootD and FTS projects.

Registration will open on 1st April and close on 1st September. The cost for the workshop is 122€ for the five days, which includes lunches and coffee breaks. There is also the possibility to join the social dinner for which the cost has yet to be determined.

Mon, September 14

Registration

Lunch

Welcome & Logistics

FTS Presentations

Coffee break

FTS Presentations

Tue, September 15

FTS Presentations

Coffee break

FTS Presentations

Lunch

WLCG Open Technical Forum #13

Conveners: Alessandro Di Girolamo (CERN), James Letts (Univ. of California San Diego (US))

Coffee break

WLCG Open Technical Forum #13

Wed, September 16

FTS Presentations

Coffee break

FTS Presentations

Lunch

Welcome & Logistics

XRootD Presentations

1 Catch up with XRootD!

This talk rounds up new features added to XRootD since the last workshop and delves into security fixes.

Speaker: Andrew Bohdan Hanushevsky (SLAC National Accelerator Laboratory (US))

2 Evolution of XRootD Monitoring: Metrics

In this contribution, we will present our work to add native support for Prometheus metrics in XRootD. We will discuss the new XrdMetrics module both from the developer and user points of view, how to configure and use the new system, and its current development status.

Speaker: Guilherme Amadio (CERN)

Coffee break

XRootD Presentations

3 Evolution of XRootD Monitoring: Logs and Traces

In this contribution, we will discuss a new XRootD detailed monitoring collector (i.e. UDP packet parser/correlator) currently under development. We will discuss its features, architecture, configuration, and deployment modes to support WLCG monitoring requirements in the future.

Speaker: Guilherme Amadio (CERN)

4 Towards WLCG-wide XRootD monitoring: deployment plans and the road to DC27

This talk gives an update on the state of a common transfer monitoring pipeline for XRootD transfers in WLCG, covering both native XRootD servers and xroot traffic over dCache. The collector is now validated and ready for large-scale deployment, and we present what deploying it at other sites involves and how we plan to drive adoption ahead of DC27.

Speaker: Panos Paparrigopoulos (CERN)

5 Improving the OSG XRootD Collector and Validating Against MonaLisa

This talk presents improvements to the OSG XRootD monitoring collector: fixing a critical t-stream parsing bug that fabricated bogus file-close records, adding topology and SciTags resolution, new Prometheus metrics, and expanded configurability for multi-VO deployments. We conclude with a validation of the collector against MonaLisa at CERN, confirming the fixes and establishing a cross-system XRootD monitoring baseline for WLCG.

Speaker: Karanjot Singh (CERN)

6 Benchmarking and Optimisation of High-Performance Data Access and Storage Systems

This CERN Openlab Summer Student project aimed to benchmark and compare different storage solutions used or considered for CERN's computing infrastructure. The main goal was to evaluate a Pure Storage appliance, HDD/SSD baselines, and CERN's production storage systems, including CephFS, XRootD and EOS. The benchmarking methodology relied on Flexible I/O (FIO) scripts designed to reasonably reproduce realistic High Energy Physics (HEP) analysis patterns and common user activities. The results of this study provide a comprehensive performance characterisation of the investigated storage solutions, helping to identify suitable candidates for the next deployments and improvements to CERN's computing services.

Speaker: Gustavo Mattos Lopes

7 Global Profiling of Open Science Data Federation Services using the Pelican Platform

Contemporary research relies heavily on computational resources and storage, with data sharing serving as a critical element. Data access remains a central challenge. The Open Science Data Federation (OSDF) project aims to establish a global scientific data distribution network by leveraging the Pelican Platform and the National Research Platform (NRP). OSDF is based on the XRootD and Pelican projects. Characterizing the performance boundaries of the Pelican Platform under various configurations, such as transfer rate limits, buffer settings, and geographic distribution, is essential. To this end, OSDF access was systematically profiled globally. The evaluation considered multiple file sizes, parallel data streams, and diverse client-server geographic relationships. This approach facilitates comprehensive monitoring of XRootD and Pelican performance across a range of scenarios. Results indicate that OSDF can deliver transfer speeds approaching the maximum capabilities of client systems.

Speaker: Fabio Andrijauskas (Univ. of California San Diego (US))

8 Experience of AI Assisted Code Improvement for XRootD

We report here our experience of using AI to make change/improvement to open source software like XRootD. We choose three real world tasks to see if AI can have a comprehensive understanding of both XRootD software stack, other software used by Xrootd (e.g. Fuse, Scitoken), and our intention. Theses tasks are: creating a separate version of xrdadler32 that does not depend on any XRootD libraries; upgrading XrdFfs (xrootdfs) from using Fuse 2.6 to Fuse 3.x with limited functionality changes; and asking AI to help us understand how Sci-tokens are passed to the XRootD clients. In each of these tasks, AI worked incredibly well as a coding assistants - it was quick to figure out underline relations within the XRootD stack, and make code change with minimum bugs. But AI does make mistakes that require human corrections. We will point out and analyze those mistakes.

Speaker: Sarah Yang

Workshop Dinner

Thu, September 17

XRootD Presentations

9 XCache - the future development menu

Discuss status and possible extensions of XCache, in particular related to:
- analysis facilities
- resource monitor
- cache control and cache consistency
- the Pelican project

Required time: 30 min

Speaker: Matevz Tadel (Univ. of California San Diego (US))

10 XCache setup and support in Germany

Several sites supporting WLCG in Germany operate XCache services. Within the recently initiated FUSE project we prepare standardized deployment procedures which match the constraints and requirements of our sites. We are working on light-weight containers and well-tested setup examples, including documentation and a dedicated monitoring service. In addition we are preparing dedicated performance test-suites ranging from low-level FIO tests to large-scale application tests based on Hammercloud.

Speaker: Raphael Kleinemuehl

Coffee break

XRootD Presentations

11 XRootD Redirectors at Fermilab: Architecture and Operations

This presentation provides an operational overview of the XRootD services hosted at Fermilab, including the USCMS AAA regional and FNAL site redirectors, as well as the StashCache redirector supporting the OSG Data Federation. We summarize the current deployment architecture, service monitoring, and operational practices.

Speaker: Lorena Lobato Pardavila (Fermi National Accelerator Lab. (US))

12 Verifying replica integrity before XRootD redirects

OpenVerify is an XRootD OFS plugin that probes candidate replicas before the client is redirected. It can locate via CMS Rucio with cmsd fallback, quarantine unhealthy sites, and export Prometheus metrics to reduce federated open failures on missing or broken files.

Speaker: Rahul Chauhan (University of Wisconsin (US))

13 An XRootD Agent as A Unified Storage Interface for INK Platform

To meet the growing and evolving needs of high-energy physics users in interactive data analysis and processing, an all-in-one platform, the Interactive Analysis Workbench (INK) is proposed and developed by IHEP CAS, as a secure and reliable bridge between users and computing clusters..
To bridge private cluster storage systems and interactive web accessing, we choose the XRootD framework combined with the FastAPI framework as a middleware to handle all filesystem access requests as well as internal access within INK. As a unified storage interface of INK, it acts as an agent to accept http access and proxy to backend server with XRootD protocol. The storage interface is one of fundamental interfaces and with it, INK has become one of the most popular interactive analysis platforms in IHEP.

Speakers: LI Haibo lihaibo, Xuantong Zhang (Institute of High Enegry Physics, Chinese Academy of Sciences (CN))

14 Secure data access to ancient data sets: XRootD in and for data preservation

Going back in time by about 30 years or more, the CERNLIB library was used by a large number of experiments and collaborations, across a huge number of platforms and architectures. Written (mostly) in C and Fortran, it contained a large number of highly optimized tools, among them the "Physics Analysis Workstation (PAW)", a popular tool to visualize scientific data at the time, and the predecessor of Root. While no longer officially supported for more than 20 years, CERNLIB is still alive and plays an important role in data preservation. This presentation tells the story about how xrootd came into the game of data preservation, and how it can be used in this context, within the original frameworks of old experiments.

Speaker: Dr Ulrich Schwickerath (CERN)

Lunch

XRootD Presentations

15 XRootD Remote Reads for WLCG Data Challenge

xrd-readgen generates controlled, measured XRootD remote-read traffic against federation redirectors and site endpoints for WLCG data challenges. This talk walks through its interfaces, internal design, and client-side metrics, and invites comments and suggestions to improve the tool.

Speaker: Rahul Chauhan (University of Wisconsin (US))

16 Update on OU_OSCER_ATLAS backend storage migration from XRootD to CephFS

Update on OU_OSCER_ATLAS backend storage migration from XRootD to CephFS

Speaker: Horst Severini (University of Oklahoma (US))

17 Real-time checksums in XRootD

This talk describes the new real-time checksum capability in XRootD.

Speaker: Andrew Bohdan Hanushevsky (SLAC National Accelerator Laboratory (US))

18 uCache: Transparent Client-Side Caching for XRootD

High-energy physics analyses repeatedly process the same data as physicists refine algorithms and test new ideas. When the data are read from remote storage, each iteration incurs network latency and depends on shared-storage throughput, which can vary substantially under load. We present uCache (xrd-ucache), a transparent cache implemented as an XRootD client plugin that requires neither server-side deployment nor changes to analysis code. It uses local storage on the analysis machine as a cache layer between the network and memory. The cache stores only the byte ranges read by an analysis and can also rebuild cached data into a branch-aligned, recompressed form, eliminating most of the input/output and decompression costs of subsequent passes. We benchmark uCache using a realistic physics analysis of public CMS data, with both TTree and RNTuple containers, on machines ranging from a 6-core desktop to a 192-core facility node. uCache is open source under the MIT license: https://github.com/drkovalskyi/xrd-ucache

Speaker: Dmytro Kovalskyi (Massachusetts Inst. of Technology (US))

Coffee break

XRootD Presentations

19 XRootD Architectures for modern storage use cases

Given the rising increase in costs for procuring fast storage, this talk aims to cover some basic XRootD Architectures to handle different use cases and storage specifications, as well as a brief overview on the cost/benefit of each approach.

Speaker: Jyothish Thomas (STFC)

20 Pelican: Building out XRootD functionality via plugins

For the Pelican Platform (https://pelicanplatform.org/), XRootD is used as the core of the data movement: whether part of the origin or cache service, when data is moved via HTTPS, XrdHttp can be found.

Doing the integration between Pelican and XRootD has required multiple new plugins into the core. They include:

• OSS storage: connecting XRootD to new storage types.
• XrdCl: providing new behavior to the caching proxy layer.
• N2N: more flexible remapings of data to alternative prefixes.
• OSS layering: adding specific functionality to the OSS stack, such as a new "persist on successful close" approach or deadlock detection.
• HTTP plugins: providing simple RESTful APIs to layers, like the cache control, that are not otherwise exported via HTTPS.

This presentation will highlight the strategy Pelican takes toward plugins and provide an overview of the new plugins we've written over the past year

Speaker: Brian Paul Bockelman (University of Wisconsin (US))

WLCG Open Technical Forum #13

Fri, September 18

XRootD Presentations

21 XrdHttp and XrdHttpTPC: The 12-Month Diff

This presentation covers twelve months of evolution in the XrdHttp and XrdHttpTPC functionalities of XRootD. These include a new CORS plugin developed to address the browser-based data analysis use case of the LHCb experiment, the WLCG HTTP-TPC data integrity check initiative and how it has been implemented, and the story behind a surprising and sudden memory increase that led to Out-of-Memory kills on the production XRootD EOSCTA clusters just after the end of Run 3.

Speaker: Cedric Caffy (CERN)

22 HTTP/XRootD clients and ROOT - Back on the case

Recent contributions to the XRootD client component have opened the possibility of using it as a multiprotocol client, supporting basic features of HTTP and S3.
This talk introduces the ongoing work to enable the ROOT framework to access HTTP and S3 servers through this XrdCl component, with the medium term goal to provide a working alternative to the Davix library.
We discuss the minimal features that are needed to achieve the objective and the ones that need to be added, trying to establish a workplan made of integration steps that cover authentication, basic features and performance-oriented ones.

Speaker: Fabrizio Furano (CERN)

23 A Native XRootD Path for GFAL Workflows

GFAL command-line tools provide a convenient, uniform interface to heterogeneous storage. For protocols already supported by XRootD, however, much of the underlying functionality exists natively but is spread across xrdfs, xrdcp, XrdCl, XrdClHttp, and the Python bindings.
This presentation describes ongoing work toward a coherent native XRootD interface for common GFAL workflows. An exploratory fsspec-based implementation served as an executable compatibility study, clarifying the required semantics, ergonomics, and testing strategy. The resulting design extends the existing XRootD stack instead of introducing another transfer engine: xrdfs provides a unified command surface, copy operations reuse the established xrdcp implementation, and reusable functionality lives in XrdCl, XrdClHttp, and the Python bindings.
The same architecture supports WLCG Tape REST operations and enables more direct Rucio and DIRAC integrations. We present the current implementation, compatibility boundaries, and remaining work.

Speaker: Luis Antonio Obis Aparicio (CERN)

24 New experimental XRootD plug-ins & R&D

I will present the design of two experimental authentication plugins:

---

• OAUTH2 for https:// and roots:// in XRootD
• SSH authentication for roots:// in XRootD

---

and can optionally introduce few other R&D projects/ideas:

---

• XrdHttpKrb5 Kerberos Authentication support in XrdHttp
• llhttp high-performance HTTP header parsing library for XRootD/XrdHttp
• http2 support in XRootD using nghttp2
• XrdClJournalCache client plugin caching byte-ranges not blocks as a local journal, pre-configured xjcd forward proxy for http(s): and root(s):
• embeddable NFS4.1 C++ server (EOS & XRootD) with TLS, KRB5 and still missing NFS over RDMA support
• kernel-resident network filesystem client over HTTPS and RDMA usable in LAN and WAN for XRootD

---

Speaker: Andreas Joachim Peters (CERN)

Coffee break

Workshop Wrap-up

Boxed lunch (take away)