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https://issues.apache.org/jira/browse/ZOOKEEPER-107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12705794#action_12705794
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Benjamin Reed commented on ZOOKEEPER-107:
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sounds great henry! it would be great if you could work on this.
i think we have two strategies:
1) have the cluster agree on a list of servers and use the atomic broadcast to
agree on changes. (this might be a bit more difficult with the flexible quorum
configuration. right flavio?) this is mostly in line with your first three
points. btw, i don't think you need to quiesce for this or even do the sync. i
think you can do a conditional update.
2) use some external resource file indicated by a URL to define the machines
that make up a cluster. this is in line with your last point and you hint at
this with your first point.
i think the first approach is safer and more reliable. the second is easier to
implement and easier to see what is going on, but i during transition time you
have a problem as the resource file propagates through the cluster. (you could
have different members with different views.)
the thing i was thinking of for the first option is exposing the cluster config
through a znode '/.zookeeper/ensemble' or something like that. then changing
the configuration would be as "simple" as conditionally setting a new version
of that file. the tricky part is that you could only commit the change if you
have a quorum of followers in both the old and the new configuration. this
seems to be in line with what you are thinking correct?
> Allow dynamic changes to server cluster membership
> --------------------------------------------------
>
> Key: ZOOKEEPER-107
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-107
> Project: Zookeeper
> Issue Type: Improvement
> Components: server
> Reporter: Patrick Hunt
>
> Currently cluster membership is statically defined, adding/removing hosts
> to/from the server cluster dynamically needs to be supported.
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