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Full cluster restart upgrade

A full cluster restart upgrade requires that you shut all nodes in the cluster down, upgrade them, and restart the cluster. A full cluster restart was required when upgrading to major versions prior to 6.x. Elasticsearch 6.x supports rolling upgrades from Elasticsearch 5.6. Upgrading to 6.x from earlier versions requires a full cluster restart. See the Upgrade paths table to verify the type of upgrade you need to perform.

To perform a full cluster restart upgrade:

  1. Disable shard allocation.

  2. Stop indexing and perform a synced flush.

    Performing a synced-flush speeds up shard recovery.

  3. Stop any machine learning jobs that are running. See {xpack-ref}/stopping-ml.html[Stopping Machine Learning].

  4. Shutdown all nodes.

  5. Upgrade all nodes.

  6. Upgrade any plugins.

    Use the elasticsearch-plugin script to install the upgraded version of each installed Elasticsearch plugin. All plugins must be upgraded when you upgrade a node.

  7. Start each upgraded node.

    If you have dedicated master nodes, start them first and wait for them to form a cluster and elect a master before proceeding with your data nodes. You can check progress by looking at the logs.

    As soon as the minimum number of master-eligible nodes have discovered each other, they form a cluster and elect a master. At that point, you can use _cat/health and _cat/nodes to monitor nodes joining the cluster:

    GET _cat/health

GET _cat/nodes

    The status column returned by _cat/health shows the health of each node in the cluster: red, yellow, or green.

  8. Wait for all nodes to join the cluster and report a status of yellow.

    When a node joins the cluster, it begins to recover any primary shards that are stored locally. The _cat/health API initially reports a status of red, indicating that not all primary shards have been allocated.

    Once a node recovers its local shards, the cluster status switches to yellow, indicating that all primary shards have been recovered, but not all replica shards are allocated. This is to be expected because you have not yet reenabled allocation. Delaying the allocation of replicas until all nodes are yellow allows the master to allocate replicas to nodes that already have local shard copies.

  9. Reenable allocation.

    When all nodes have joined the cluster and recovered their primary shards, reenable allocation by restoring cluster.routing.allocation.enable to its default:

    PUT _cluster/settings
{
  "persistent": {
    "cluster.routing.allocation.enable": null
  }
}

    Once allocation is reenabled, the cluster starts allocating replica shards to the data nodes. At this point it is safe to resume indexing and searching, but your cluster will recover more quickly if you can wait until all primary and replica shards have been successfully allocated and the status of all nodes is green.

    You can monitor progress with the _cat/health and _cat/recovery APIs:

    GET _cat/health

GET _cat/recovery

  10. Restart machine learning jobs.