High‑Availability Architecture of TuGraph‑DB: Design, Planning, and Deployment

The article introduces the high‑availability (HA) architecture of TuGraph‑DB, beginning with a definition of HA, its importance for online services, and the industry‑standard metrics (e.g., 4‑9 availability, RTO/RPO).

It describes common HA patterns, focusing on the primary‑backup replication model and its limitations, then presents TuGraph‑DB’s HA solution based on the Raft consensus algorithm, highlighting Raft’s leader‑based service, strong consistency through log replication, safety guarantees, and fault tolerance when fewer than half of the nodes fail.

The document details the Raft‑driven cluster design: enabling HA with the enable_ha and ha_conf parameters, automatic leader election, request routing for reads and writes, log‑driven write consistency, and the use of snapshots to accelerate follower synchronization without blocking MVCC reads.

Client‑side design is also covered, emphasizing the need for connections to all cluster nodes, automatic leader discovery, and load‑balancing of read requests across followers to improve performance.

Future plans include introducing a Witness role for small‑scale deployments, on‑demand snapshot generation to reduce storage overhead, and expanding the HA toolchain (e.g., cluster‑wide online import, snapshot utilities, and richer client APIs).

References to detailed deployment guides and SDKs for C++, Java, and Python are provided, along with visual diagrams illustrating the architecture.