[ZOOKEEPER-3393] Read-only file system may make the whole ZooKeeper cluster to be unavailable.

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.4.12, 3.4.14
• Component/s: leaderElection, server
• Assignee: Unassigned
• Reporter: Jiafu Jiang
• Created: 14/May/19 01:41
• Updated: 14/May/19 01:41

Description

Say we have 3 nodes: zk1, zk2, and zk3, zk3 is the leader.

If the file system of the ZooKeeper data directory of the leader is read-only due to some hardware error, the leader will exit and begin a new election.

But the election will keep looping because the new leader may be zk3 again, but zk3 will fail to write epoch to disk due to read-only file system.

 

Since we have 3 nodes, if only one of them is in problem, should the ZooKeeper cluster be available? If the answer is yes, then we ought to fix this problem.