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added docs

This commit is contained in:
Boaz Leskes 2015-08-25 15:03:17 +02:00
parent c7c65b626f
commit f70ed876d6
2 changed files with 27 additions and 6 deletions
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18
docs/reference/modules/discovery/zen.asciidoc
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@ -108,12 +108,18 @@ considered failed. Defaults to `3`.
The master node is the only node in a cluster that can make changes to the
cluster state. The master node processes one cluster state update at a time,
applies the required changes and publishes the updated cluster state to all
the other nodes in the cluster. Each node receives the publish message,
updates its own cluster state and replies to the master node, which waits for
all nodes to respond, up to a timeout, before going ahead processing the next
updates in the queue. The `discovery.zen.publish_timeout` is set by default
to 30 seconds and can be changed dynamically through the
<<cluster-update-settings,cluster update settings api>>
the other nodes in the cluster. Each node receives the publish message, acknowledges
it but do *not* yet apply it. If the master does not receive acknowledgement from
at least `discovery.zen.minimum_master_nodes` nodes within a certain time (controlled by
the `discovery.zen.commit_timeout` setting and defaults to 30 seconds) the cluster state
change is rejected.
Once enough nodes have responded, the cluster state is committed and a message will
be sent to all the nodes. The nodes then proceed and apply the new cluster state to their
internal state. The master node waits for all nodes to respond, up to a timeout, before
going ahead processing the next updates in the queue. The `discovery.zen.publish_timeout` is
set by default to 30 seconds and is measured from the moment the publishing started. Both
timeout settings can be changed dynamically through the <<cluster-update-settings,cluster update settings api>>
[float]
[[no-master-block]]

15
docs/resiliency/index.asciidoc
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@ -55,6 +55,21 @@ If you encounter an issue, https://github.com/elasticsearch/elasticsearch/issues
We are committed to tracking down and fixing all the issues that are posted.
[float]
=== Use two phase commit for Cluster State publishing (STATUS: ONGOING)
A master node in Elasticsearch continuously https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-discovery-zen.html#fault-detection[monitors the cluster nodes]
and removes any node from the cluster that doesn't respond to it's pings in a timely
fashion. If the master is left with less nodes than the `discovery.zen.minimum_master_nodes`
settings, it will step down and a new master election will start.
When a network partition occurs causing a master to loose many followers, there is a
short window of time until detects it and master steps down. During that window, the
master may erroneously accept and ack cluster state changes. To avoid this, we introduce
a new phase to cluster state publishing where the proposed cluster state is sent to all nodes
but is not yet committed. Only once enough nodes (`minimum_master_nodes`) actively acknowledge
the change, it is committed and commit messages are sent to the nodes. See See {GIT}13062[#13062].
[float]
=== Make index creation more user friendly (STATUS: ONGOING)