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The Storage Group in the CERN IT Department operates several Ceph storage clusters with an overall capacity exceeding 100 PB. Ceph is a crucial component of the infrastructure delivering IT services to all the users of the Organization as it provides: i) Block storage for OpenStack, ii) CephFS, used as persistent storage by containers (OpenShift and Kubernetes) and as shared filesystems by HPC clusters and iii) S3 object storage for cloud-native applications, monitoring and software distribution across the WLCG. The Ceph infrastructure at CERN is being rationalized and restructured to allow for the implementation of a Business Continuity/Disaster Recovery plan. In this paper, we give an overview of how we transitioned from a single cluster providing block storage to multiple ones, enabling Storage Availability zones, and how block storage backups can be achieved. We also illustrate future plans for file systems backups through cback,a restic-based scalable orchestrator, and how S3 implements data immutability and provides a highly available, Multi-Data Centre object storage service. [ABSTRACT FROM AUTHOR]

The CERN IT Storage group operates multiple distributed storage systems to support all CERN data storage requirements. The storage and distribution of physics data generated by LHC and non-LHC experiments is one of the biggest challenges the group has to take on during LHC Run-3. EOS [1], the CERN distributed disk storage system is playing a key role in LHC data-taking. During the first ten months of 2022, more than 440PB have been written by the experiments and 2.9EB have been read out. The data storage requirements of LHC Run-3 are higher than what was previously delivered. The storage operations team has started investigating multiple areas to upgrade and optimize the current storage resources. A new, dedicated and redundant EOS infrastructure based on 100Gbit servers was installed, commissioned and deployed for the ALICE Online and Offline (O2) project. This cluster can sustain high-throughput data transfer between the ALICE Event Processing Nodes (EPN) and the CERN's data center. This paper will present the architecture, techniques and workflows in place allowing EOS to deliver fast, reliable and scalable data storage to meet experiment needs during LHC Run-3 and beyond. [ABSTRACT FROM AUTHOR]