[jira] [Created] (ZOOKEEPER-1692) Add support for single member ensemble

["Thawan Kooburat (JIRA)" <ji...@apache.org>]

Thawan Kooburat created ZOOKEEPER-1692:
------------------------------------------

             Summary: Add support for single member ensemble
                 Key: ZOOKEEPER-1692
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1692
             Project: ZooKeeper
          Issue Type: Improvement
          Components: quorum
    Affects Versions: 3.4.0
            Reporter: Thawan Kooburat
            Assignee: Thawan Kooburat
            Priority: Minor


In the past, we ran into problem where quorum could not be formed multiple times. It take a while to investigate the root cause and fix the problem.

Our current solution is to make it possible to run a quorum with a single member in it. Unlike standalone mode, it has to run as LeaderZooKeeper server, so that the observers can connect to it. 

This will allow the operator to use this workaround to bring back the ensemble quickly while investigating the problem in background.


The main problem here is to allow the observers to connect with the leader when the quorum size is reduced to one. We don't want to update the (static) configuration on the observer since it require server restart. We are thinking of allowing the observer to connect to any participant which declared that it is the leader without running the leader election algorithm (because it won't have enough votes).  


--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira