Ceph is an open source software designed to provide highly scalable object-, block- and file-based storage under a unified system.
Ceph storage clusters are designed to run on commodity hardware, using an algorithm called CRUSH (Controlled Replication Under Scalable Hashing) to ensure that data is evenly distributed across the cluster and that all cluster nodes are able to retrieve data quickly without any centralized bottlenecks.
Ceph object storage is accessible through Amazon Simple Storage Service (S3) and OpenStack Swift Representational State Transfer (REST)-based application programming interfaces (APIs) and a native API for integration with software applications.
Ceph block storage makes use of a Ceph Block Device, which is a virtual disk that can be attached to bare-metal Linux-based servers or to virtual machines (VMs). The Ceph Reliable Autonomic Distributed Object Store (RADOS) provides block storage capabilities such as snapshots and replication. The Ceph RADOS Block Device (RBD) is integrated to work as a back end with OpenStack Block Storage.
Ceph file storage makes use of the Portable Operating System Interface (POSIX)-compliant Ceph file system (Ceph FS) to store data in a Ceph storage cluster. Ceph FS uses the same clustered system as Ceph block storage and Ceph object storage.
Inktank Storage Inc. sells a subscription-based, commercially supported version of Ceph. Sage Weil, the chief technology officer at Inktank, created Ceph as part of a Ph.D project at the University of California, Santa Cruz. The Ceph open source project started in 2004, and the software became available under an open source license in 2006.