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[[modules-cluster]]
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== Shard allocation and cluster-level routing
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2015-06-22 17:49:45 -04:00
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One of the main roles of the master is to decide which shards to allocate to
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which nodes, and when to move shards between nodes in order to rebalance the
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cluster.
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There are a number of settings available to control the shard allocation process:
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2016-07-12 11:47:28 -04:00
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* <<shards-allocation>> lists the settings to control the allocation and
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rebalancing operations.
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* <<disk-allocator>> explains how Elasticsearch takes available disk space
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into account, and the related settings.
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* <<allocation-awareness>> and <<forced-awareness>> control how shards can
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be distributed across different racks or availability zones.
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* <<allocation-filtering>> allows certain nodes or groups of nodes excluded
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from allocation so that they can be decommissioned.
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Besides these, there are a few other <<misc-cluster,miscellaneous cluster-level settings>>.
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All of the settings in this section are _dynamic_ settings which can be
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updated on a live cluster with the
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<<cluster-update-settings,cluster-update-settings>> API.
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include::cluster/shards_allocation.asciidoc[]
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include::cluster/disk_allocator.asciidoc[]
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include::cluster/allocation_awareness.asciidoc[]
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include::cluster/allocation_filtering.asciidoc[]
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include::cluster/misc.asciidoc[]
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