Ceph

Ceph is a unified distributed storage platform that provides object, block, and file storage services from a single cluster, designed for petabyte-scale deployments with no single point of failure. Originally developed by Sage Weil in 2004 as part of his doctoral research at the University of California, Santa Cruz, Ceph has become the leading open-source software-defined storage solution, adopted as the default storage backend for major cloud platforms including Red Hat OpenStack and many private cloud deployments. The platform's architecture is built on RADOS (Reliable Autonomic Distributed Object Store), a self-healing and self-managing object store that automatically rebalances data across OSDs (Object Storage Daemons) using the CRUSH (Controlled Replication Under Scalable Hashing) algorithm, which eliminates the need for centralized metadata lookup tables and enables clients to calculate data placement directly. Ceph exposes three storage interfaces: RADOS Gateway (RGW) provides S3 and Swift-compatible object storage with multi-tenancy and bucket versioning, RBD (RADOS Block Device) provides thin-provisioned block storage with snapshots and cloning for virtual machines and containers, and CephFS provides a POSIX-compliant distributed file system with metadata servers (MDS) for hierarchical namespace management. The platform supports erasure coding for storage efficiency, replication factors of 2x or 3x for durability, data-at-rest encryption, and quality of service tiering. Major organizations including CERN, DreamHost, Bloomberg, and Deutsche Telekom operate Ceph clusters storing exabytes of data. Sponsored primarily by Red Hat, Ceph is available under the LGPL 2.1 license.