Disable shard allocation.

When you shut down a node, the allocation process waits for index.unassigned.node_left.delayed_timeout (by default, one minute) before starting to replicate the shards on that node to other nodes in the cluster, which can involve a lot of I/O. Since the node is shortly going to be restarted, this I/O is unnecessary. You can avoid racing the clock by disabling allocation of replicas before shutting down the node:

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

Stop non-essential indexing and perform a synced flush. (Optional)

While you can continue indexing during the upgrade, shard recovery is much faster if you temporarily stop non-essential indexing and perform a synced-flush.

POST _flush/synced

When you perform a synced flush, check the response to make sure there are no failures. Synced flush operations that fail due to pending indexing operations are listed in the response body, although the request itself still returns a 200 OK status. If there are failures, reissue the request.

Temporarily stop the tasks associated with active machine learning jobs and datafeeds. (Optional)

If your machine learning indices were created before 6.x, you must reindex the indices.

If your machine learning indices were created in 6.x, you can:

+ When you disable upgrade mode, the jobs resume using the last model state that was automatically saved. This option avoids the overhead of managing active jobs during the upgrade and is faster than explicitly stopping datafeeds and closing jobs.

Shut down a single node.

Upgrade the node you shut down.

To upgrade using a Debian or RPM package:

To upgrade using a zip or compressed tarball:

When you extract the zip or tarball packages, the elasticsearch-n.n.n directory contains the Elasticsearch config, data, logs and plugins directories.

We recommend moving these directories out of the Elasticsearch directory so that there is no chance of deleting them when you upgrade Elasticsearch. To specify the new locations, use the ES_PATH_CONF environment variable and the path.data and path.logs settings. For more information, see Important Elasticsearch configuration.

The Debian and RPM packages place these directories in the appropriate place for each operating system. In production, we recommend installing using the deb or rpm package.

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.

Start the upgraded node.

Start the newly-upgraded node and confirm that it joins the cluster by checking the log file or by submitting a _cat/nodes request:

GET _cat/nodes

Reenable shard allocation.

Once the node has joined the cluster, remove the cluster.routing.allocation.enable setting to enable shard allocation and start using the node:

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

Wait for the node to recover.

Before upgrading the next node, wait for the cluster to finish shard allocation. You can check progress by submitting a _cat/health request:

GET _cat/health?v

Wait for the status column to switch from yellow to green. Once the node is green, all primary and replica shards have been allocated.

During a rolling upgrade, primary shards assigned to a node running the new version cannot have their replicas assigned to a node with the old version. The new version might have a different data format that is not understood by the old version.

If it is not possible to assign the replica shards to another node (there is only one upgraded node in the cluster), the replica shards remain unassigned and status stays yellow.

In this case, you can proceed once there are no initializing or relocating shards (check the init and relo columns).

As soon as another node is upgraded, the replicas can be assigned and the status will change to green.

Shards that were not sync-flushed might take longer to recover. You can monitor the recovery status of individual shards by submitting a _cat/recovery request:

GET _cat/recovery

If you stopped indexing, it is safe to resume indexing as soon as recovery completes.

Repeat

When the node has recovered and the cluster is stable, repeat these steps for each node that needs to be updated.

Restart machine learning jobs.

If you temporarily halted the tasks associated with your machine learning jobs, use the set upgrade mode API to return them to active states:

POST _ml/set_upgrade_mode?enabled=false

If you closed all machine learning jobs before the upgrade, open the jobs and start the datafeeds from Kibana or with the open jobs and start datafeed APIs.