Software Engineer

Job Posting Organization:
CERN, the European Organization for Nuclear Research, is a leading laboratory for particle physics, established to probe the fundamental structure of the universe. It employs physicists and engineers who utilize the world's largest and most complex scientific instruments to study fundamental particles. CERN is known for its groundbreaking contributions to science, including the invention of the World Wide Web. The organization operates in multiple countries and employs a diverse workforce, fostering an environment of innovation and collaboration.

Job Overview:
The Software Engineer position at CERN involves working with the Storage and Data Management Group within the IT Department to evolve the data storage systems used at the Large Hadron Collider (LHC) and its international partners. The role focuses on the design, evolution, and operation of large-scale distributed storage services for CERN's cloud and computing infrastructures. The successful candidate will engage with Ceph-based solutions, ensuring high availability and performance across multi-datacenter environments. This position requires troubleshooting complex system-wide issues and optimizing storage architectures for demanding workloads, including high-performance computing (HPC) and artificial intelligence/machine learning (AI/ML). The role also emphasizes continuous improvement in automation, deployment, and observability, aligning with modern DevOps practices.

Duties and Responsibilities:
The duties and responsibilities of the Software Engineer include co-leading the management and operations of distributed disk storage, block, object, and filesystem services based on mainstream open-source technologies such as Ceph and NFS. The engineer will participate in the evolution of architecture and design of storage services for CERN's cloud and compute infrastructure, as well as core business applications related to physics data processing, ML/AI, and HPC use cases. Responsibilities also include integrating, troubleshooting, and maintaining distributed disk storage systems at scale across multiple availability zones and data centers. The engineer will contribute to documentation, development, optimization, and further automation of storage services, as well as engage in change management, incident response, and user support. Additionally, the role involves liaising with key stakeholders both inside and outside the IT department.

Required Qualifications:
Candidates must possess a Master's degree or equivalent relevant experience in Computer Science or a related field. A deep understanding of Linux and the architecture of storage and filesystems, including high availability and failure-domain, is essential. Knowledge of the POSIX permissions model, POSIX ACLs, and authentication/authorization concepts such as CephX and Kerberos for NFS is required. Proficiency in at least one systems programming language, ideally C/C++, or other high-performance languages like Rust or Golang is necessary. Good knowledge of scripting languages such as Python or shell for automation of deployment and testing is also required. Solid debugging skills for troubleshooting complex distributed environments and performance tuning are essential, along with experience in diagnosing complex system-wide issues spanning hardware, network, and software layers. Familiarity with DevOps skills, including CI/CD, Gitlab, containerization, monitoring, and system observability tools like Prometheus and Grafana is also important. Strong collaboration and communication skills are necessary to work effectively with multiple cross-functional teams.

Educational Background:
The educational background required for this position includes a Master's degree or equivalent in Computer Science or a related field. This educational foundation is crucial for understanding the complexities of software engineering and data management in a high-tech environment like CERN.

Experience:
Candidates should have a deep understanding of Linux systems and the architecture of storage and filesystems. Experience in managing and operating distributed storage systems, particularly with Ceph and NFS, is highly desirable. The role requires a proven track record of troubleshooting complex issues in distributed environments and optimizing performance for demanding workloads. Familiarity with DevOps practices and tools is also beneficial, as is experience in collaborating with cross-functional teams.

Languages:
Fluency in spoken and written English is mandatory, with a commitment to learn French being a valuable asset. Proficiency in additional languages may enhance communication within the diverse workforce at CERN.

Additional Notes:
This position is a limited duration contract for 5 years, with the possibility of extension up to 8 years and eligibility for an indefinite contract tenure. The working hours are set at 40 hours per week, with hybrid job flexibility. The role may require work during nights, Sundays, and official holidays, as well as stand-by duty when necessary. The job grade is classified as 6-7, and the reference for this position is IT-SD-GSS-2026-96-LD. CERN offers a competitive salary that is tax-free, along with 30 days of paid leave per year, comprehensive health insurance coverage, and various family allowances depending on individual circumstances. A relocation package is also available based on individual needs.