[ZOOKEEPER-1075] Zookeeper Server cannot join an existing ensemble if the existing ensemble doesn't already have a quorum

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 3.3.2
• Component/s: leaderElection

Environment

Windows 7

• Assignee: Unassigned
• Reporter: Vishal Kathuria
• Created: 25/May/11 21:39
• Updated: 27/May/11 07:07
• Resolved: 26/May/11 18:19

Description

Here is the sequence of steps that reproduces the problem.
On a 3 server ensemble,
1. Bring up two servers (say 1 and 2). Lets say 1 is leading.
2. Bring down 2
3. Bring up 2.
4. 2 gets a notification from 1 that it is leading but 2 doesn't accept it as a leader since it cannot find one other node that thinks 1 is the leader.

So the ensemble gets stuck where 2 isn't following. If at this point, 3 comes up, then one of 2 & 3 will become a leader and 1 will keep thinking it is the leader.

I am working on a patch to fix this issue.