What happens if a TiDB leader goes down? How does TiDB use Raft to ensure data security and consistency?

Question

If one leader node in TiDB is down, will my data get lost or the service be affected? How long will it be until the service recovers (i.e. a new leader is re-elected)?

Answer 1

TiDB uses Raft to synchronize data among multiple replicas and guarantees the strong consistency of data. If one replica goes down, the other replicas can guarantee data security. The default number of replicas in each Region is 3. Based on the Raft protocol, a leader is elected in each Region, and if a single Region leader fails, a new Region leader is soon elected after a maximum of 2 * lease time (lease time is 10 seconds).