Ceph’s object storage system offers a significant feature compared to many object storage systems available today: Ceph provides a traditional file system interface with POSIX semantics. Object storage systems are a significant innovation, but they complement rather than replace traditional file systems. As storage requirements grow for legacy applications, organizations can configure their legacy applications to use the Ceph file system too! This means you can run one storage cluster for object, block and file-based data storage.
Ceph’s file system runs on top of the same object storage system that provides object storage and block device interfaces. The Ceph metadata server cluster provides a service that maps the directories and file names of the file system to objects stored within RADOS clusters. The metadata server cluster can expand or contract, and it can rebalance the file system dynamically to distribute data evenly among cluster hosts. This ensures high performance and prevents heavy loads on specific hosts within the cluster.