Ceph primarily utilizes its own Ceph File System (CephFS), a highly scalable, distributed, and POSIX-compatible file system.
Understanding CephFS
CephFS is not just an ordinary file system; it's a critical component of the Ceph storage platform. It's designed to provide file access to a Red Hat Ceph Storage cluster, leveraging the underlying distributed object store for its robust capabilities.
- Built on RADOS: CephFS is architecturally built directly on top of Ceph's distributed object store, known as RADOS (Reliable Autonomic Distributed Object Storage). This foundation allows CephFS to inherit the incredible scalability, fault tolerance, and self-healing properties that are hallmarks of Ceph's design.
- POSIX Compatibility: A key feature of CephFS is its compatibility with POSIX (Portable Operating System Interface) standards. This means it behaves like a traditional file system for applications, supporting standard file operations, permissions, and directory structures. Wherever possible, CephFS employs POSIX semantics to ensure broad compatibility and ease of use.
- Unified Storage: Ceph's architecture is unique in that it can present storage in multiple ways from a single cluster: block storage (RBD), object storage (RGW), and file storage (CephFS). This flexibility makes Ceph a versatile solution for various data storage needs.
Key Characteristics of CephFS
CephFS offers several advantages for organizations requiring a robust, shared file system:
- Scalability: It can scale from a few terabytes to many petabytes, handling vast amounts of data and concurrent users.
- High Availability: Thanks to its RADOS backend, CephFS distributes data and metadata across multiple nodes, ensuring high availability and resilience against hardware failures.
- Shared Access: Multiple clients can mount and access the same CephFS instance simultaneously, making it ideal for shared workloads and collaborative environments.
- Performance: Designed for high-performance applications, CephFS can deliver excellent throughput and IOPS, especially when handling large files and complex directory structures.
Ceph Storage Components Overview
To better understand CephFS's role, it's helpful to see how it fits within the broader Ceph ecosystem.
| Component | Description |
|---|---|
| CephFS | The distributed, POSIX-compatible file system that provides file access. |
| RADOS | (Reliable Autonomic Distributed Object Storage) The core distributed object store layer upon which all Ceph interfaces are built. |
| RBD | (RADOS Block Device) Provides block storage devices for virtual machines and bare-metal servers. |
| RGW | (RADOS Gateway) Offers object storage with Amazon S3 and OpenStack Swift compatible APIs. |
| OSDs | (Object Storage Daemons) The fundamental storage units in Ceph clusters that store data as objects. |
| Monitors | Maintain cluster state, maps, and provide a reliable foundation for all Ceph operations. |
| MDS | (Metadata Servers) Manage the metadata for CephFS, crucial for directory structure and file operations. |
In summary, when discussing the file system used by Ceph, the answer is CephFS, a powerful and flexible solution built upon the distributed object storage capabilities of RADOS.
