elasticsearch/docs/reference/migration/migrate_8_0/node.asciidoc

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[[breaking_80_node_changes]]
=== Node changes

//NOTE: The notable-breaking-changes tagged regions are re-used in the
//Installation and Upgrade Guide
//tag::notable-breaking-changes[]

// end::notable-breaking-changes[]

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==== Removal of `node.max_local_storage_nodes` setting

The `node.max_local_storage_nodes` setting was deprecated in 7.x and
has been removed in 8.0. Nodes should be run on separate data paths
to ensure that each node is consistently assigned to the same data path.

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==== Change of data folder layout

Each node's data is now stored directly in the data directory set by the
`path.data` setting, rather than in `${path.data}/nodes/0`, because the removal
of the `node.max_local_storage_nodes` setting means that nodes may no longer
share a data path. At startup, Elasticsearch will automatically migrate the data
path to the new layout. This automatic migration will not proceed if the data
path contains data for more than one node. You should move to a configuration in
which each node has its own data path before upgrading.

If you try to upgrade a configuration in which there is data for more than one
node in a data path then the automatic migration will fail and Elasticsearch
will refuse to start. To resolve this you will need to perform the migration
manually. The data for the extra nodes are stored in folders named
`${path.data}/nodes/1`, `${path.data}/nodes/2` and so on, and you should move
each of these folders to an appropriate location and then configure the
corresponding node to use this location for its data path. If your nodes each
have more than one data path in their `path.data` settings then you should move
all the corresponding subfolders in parallel. Each node uses the same subfolder
(e.g. `nodes/2`) across all its data paths.