# `Raft:` Explain `Replica`
+ **_In 3-replica-config `TiKV` cluster, will the system be available as long as one of them is alive?_**
  + `Raft` replica is not a full copy of the same data, we only need to replicate logs to **more than half** of the nodes during write operation
  + If there are only 1 replica alive among 3 replicas, then the system is **broken**:
    + The is no guarantee that data is complete
    + Unable to meet the requirement that logs need to be replicated to majority nodes
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