# High Availability Features Of Tikv Servers

+ Failure recover
  + Few follower failures or quarantines do not affect Leader services
  + After leader failure or isolation, the follower will automatically start the elect process when the heartbeat exceeds
  + As long as more than half of the nodes are alive, a new leader will be selected to recover service
+ consistency of data
  + When writing data, the Leader ensures that the logs are copied to most nodes
  + When some nodes fail or are quarantined, as long as more than half of the nodes are alive, at least one of them contains the latest logs
  + The Raft protocol always selects the node containing the latest logs as the leader
  + In summary, if the constraints are met, no data loss will occur 

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  1. Failure recover 
    1. Few follower failures or quarantines do not affect Leader services 
    2. After leader failure or isolation, the follower will automatically start the elect process when the heartbeat exceeds 
    3. As long as more than half of the nodes are alive, a new leader will be selected to recover service 
  2. consistency of data 
    4. When writing data, Leader ensures that logs are copied to most nodes 
    5. When some nodes fail or are quarantined, as long as more than half of the nodes are alive, at least one of them contains the latest logs 
    6. The Raft protocol always selects the node containing the latest logs as the leader 
    7. In summary, if the constraints are met, no data loss will occur.