Does a Leader Retain Leadership After Restart in Raft Algorithm?

[bz1988]

When a leader node in a Raft cluster restarts, does it retain its leadership role upon rejoining the cluster? Specifically, if the leader comes back online before the followers' election timeouts expire, does it continue as the leader without triggering a new election? Or does the restarting node become a follower and participate in a new election process according to the Raft protocol?

Thank you in advance

[Free Ekanayaka]

Hello,

in classic Raft information about votes received from other servers is
not persisted (only the vote that the server itself granted is
persisted). So when the leader restarts it has no way to know that it's
the leader.

One could imagine of persisting votes received from other nodes, but I'm
not sure if there are subtle the implications to consider, and it does
not feel like it is worth for most cases.

Free

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[Ejem Agbaeze]

1. If the leader comes back online before the election timeout is exhausted on the followers then it continues as the leader. Peradventure, the heartbeat was delayed by network disruption not necessarily that the leader crashed.

2. If it comes back online when the followers  have elected a new leader, it joins as a follower.

3. Or if the restarted node cannot join on the leader election provided that the followers make up a majority of the cluster and after the election it joins as follower

On Thu, 26 Sept 2024, 6:53 pm bz1988, <bojan...@gmail.com> wrote:

When a leader node in a Raft cluster restarts, does it retain its leadership role upon rejoining the cluster? Specifically, if the leader comes back online before the followers' election timeouts expire, does it continue as the leader without triggering a new election? Or does the restarting node become a follower and participate in a new election process according to the Raft protocol?

Thank you in advance

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