RGW

RADOS Gateway (RGW) is a component of the Ceph distributed storage system that provides object storage interfaces on top of the RADOS backend. RGW implements both S3 and OpenStack Swift-compatible APIs, allowing clients to store and retrieve data via RESTful HTTP requests while Ceph handles data placement, replication, and fault tolerance in the underlying cluster.

Operation and architecture: RGW runs as gateway daemons that connect to the Ceph cluster’s metadata and storage services. It can be deployed on multiple nodes to scale throughput and handle requests from many clients. Data written through RGW is stored as objects in RADOS pools; RGW manages bucket and object metadata, access control, and versioning at the gateway layer, while RADOS provides durability and replication.

Protocols and features: RGW provides S3 API compatibility (buckets, objects, access management) and Swift API compatibility for legacy clients. It supports multi-site replication to synchronize buckets across Ceph clusters, as well as bucket versioning, object tagging, and lifecycle policies. Authentication is handled through the Ceph authentication framework for internal communication, with external credentials used for S3/Swift clients.

Deployment and administration: RGW is one option for object storage within a Ceph deployment; alternatives include gateways for other protocols. It requires a functioning Ceph monitor and OSD cluster, and network latency can affect performance. RGW endpoints can be secured with TLS, and administration can be performed through Ceph tooling to manage users, buckets, and policies.

History and status: RGW has been a core part of Ceph since early releases and remains under active development. Ongoing work focuses on API compatibility, scalability, and features such as multi-site replication and integration with erasure-coded pools.