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Flavio Paiva Junqueira commented on ZOOKEEPER-29: ------------------------------------------------- Just to motivate a little more this scheme, taking the example above, suppose that each group corresponds to the set of ZooKeeper servers in a colocation. To form a quorum, we just need to get a majority of servers from a majority of groups. This gives us quorums of size 4, whereas majority quorums would require 5. This model is reasonable, though, as it is reasonable to expect that at least a majority of colocations have a majority of servers up and running. This idea actually appeared in the following citation (apologies for the self-reference): http://dslab.epfl.ch/hotdep/2005/papers/junqueira_dependent.pdf Another question that may arise is how leader election changes. With this scheme it only changes minimally. In the current trunk code, we always wait for a majority of votes, and that's because we have majority quorums hardcoded. With this patch, we check if we have a quorum, and a quorum can be a majority, as we have currently, or a different quorum system as the one of the example. > Flexible quorums > ---------------- > > Key: ZOOKEEPER-29 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-29 > Project: Zookeeper > Issue Type: New Feature > Components: server > Reporter: Patrick Hunt > Assignee: Flavio Paiva Junqueira > Fix For: 3.2.0 > > Attachments: ZOOKEEPER-29.patch, ZOOKEEPER-29.patch, > ZOOKEEPER-29.patch, ZOOKEEPER-29.patch, ZOOKEEPER-29.patch, ZOOKEEPER-29.patch > > > Moved from SourceForge to Apache. > http://sourceforge.net/tracker/index.php?func=detail&aid=1938782&group_id=209147&atid=1008547 -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.