OpenSearch/docs/reference/migration/migrate_5_0/settings.asciidoc

[[breaking_50_settings_changes]]
=== Settings changes

From Elasticsearch 5.0 on all settings are validated before they are applied.
Node level and default index level settings are validated on node startup,
dynamic cluster and index setting are validated before they are updated/added
to the cluster state.

Every setting must be a *known* setting. All settings must have been
registered with the node or transport client they are used with. This implies
that plugins that define custom settings must register all of their settings
during plugin loading using the `SettingsModule#registerSettings(Setting)`
method.

==== Node settings

The `name` setting has been removed and is replaced by `node.name`. Usage of
`-Dname=some_node_name` is not supported anymore.

==== Transport Settings

All settings with a `netty` infix have been replaced by their already existing
`transport` synonyms. For instance `transport.netty.bind_host` is no longer
supported and should be replaced by the superseding setting
`transport.bind_host`.

==== Script mode settings

Previously script mode settings (e.g., "script.inline: true",
"script.engine.groovy.inline.aggs: false", etc.) accepted the values
`on`, `true`, `1`, and `yes` for enabling a scripting mode, and the
values `off`, `false`, `0`, and `no` for disabling a scripting mode.
The variants `on`, `1`, and `yes ` for enabling and `off`, `0`,
and `no` for disabling are no longer supported.


==== Security manager settings

The option to disable the security manager `security.manager.enabled` has been
removed. In order to grant special permissions to elasticsearch users must
edit the local Java Security Policy.

==== Network settings

The `_non_loopback_` value for settings like `network.host` would arbitrarily
pick the first interface not marked as loopback. Instead, specify by address
scope (e.g. `_local_,_site_` for all loopback and private network addresses)
or by explicit interface names, hostnames, or addresses.

==== Forbid changing of thread pool types

Previously, <<modules-threadpool,thread pool types>> could be dynamically
adjusted. The thread pool type effectively controls the backing queue for the
thread pool and modifying this is an expert setting with minimal practical
benefits and high risk of being misused. The ability to change the thread pool
type for any thread pool has been removed. It is still possible to adjust
relevant thread pool parameters for each of the thread pools (e.g., depending
on the thread pool type, `keep_alive`, `queue_size`, etc.).


==== Analysis settings

The `index.analysis.analyzer.default_index` analyzer is not supported anymore.
If you wish to change the analyzer to use for indexing, change the
`index.analysis.analyzer.default` analyzer instead.

==== Ping timeout settings

Previously, there were three settings for the ping timeout:
`discovery.zen.initial_ping_timeout`, `discovery.zen.ping.timeout` and
`discovery.zen.ping_timeout`. The former two have been removed and the only
setting key for the ping timeout is now `discovery.zen.ping_timeout`. The
default value for ping timeouts remains at three seconds.

==== Recovery settings

Recovery settings deprecated in 1.x have been removed:

 * `index.shard.recovery.translog_size` is superseded by `indices.recovery.translog_size`
 * `index.shard.recovery.translog_ops` is superseded by `indices.recovery.translog_ops`
 * `index.shard.recovery.file_chunk_size` is superseded by `indices.recovery.file_chunk_size`
 * `index.shard.recovery.concurrent_streams` is superseded by `indices.recovery.concurrent_streams`
 * `index.shard.recovery.concurrent_small_file_streams` is superseded by `indices.recovery.concurrent_small_file_streams`
 * `indices.recovery.max_size_per_sec` is superseded by `indices.recovery.max_bytes_per_sec`

If you are using any of these settings please take the time to review their
purpose. All of the settings above are considered _expert settings_ and should
only be used if absolutely necessary. If you have set any of the above setting
as persistent cluster settings please use the settings update API and set
their superseded keys accordingly.

The following settings have been removed without replacement

 * `indices.recovery.concurrent_small_file_streams` - recoveries are now single threaded. The number of concurrent outgoing recoveries are throttled via allocation deciders
 * `indices.recovery.concurrent_file_streams` - recoveries are now single threaded. The number of concurrent outgoing recoveries are throttled via allocation deciders

==== Translog settings

The `index.translog.flush_threshold_ops` setting is not supported anymore. In
order to control flushes based on the transaction log growth use
`index.translog.flush_threshold_size` instead.

Changing the translog type with `index.translog.fs.type` is not supported
anymore, the `buffered` implementation is now the only available option and
uses a fixed `8kb` buffer.

The translog by default is fsynced after every `index`, `create`, `update`,
`delete`, or `bulk` request.  The ability to fsync on every operation is not
necessary anymore. In fact, it can be a performance bottleneck and it's trappy
since it enabled by a special value set on `index.translog.sync_interval`.
Now, `index.translog.sync_interval`  doesn't accept a value less than `100ms`
which prevents fsyncing too often if async durability is enabled. The special
value `0` is no longer supported.

==== Request Cache Settings

The deprecated settings `index.cache.query.enable` and
`indices.cache.query.size` have been removed and are replaced with
`index.requests.cache.enable` and `indices.requests.cache.size` respectively.

`indices.requests.cache.clean_interval has been replaced with
`indices.cache.clean_interval and is no longer supported.

==== Field Data Cache Settings

The `indices.fielddata.cache.clean_interval` setting has been replaced with
`indices.cache.clean_interval`.

==== Allocation settings

The `cluster.routing.allocation.concurrent_recoveries` setting has been
replaced with `cluster.routing.allocation.node_concurrent_recoveries`.

==== Similarity settings

The 'default' similarity has been renamed to 'classic'.

==== Indexing settings

The `indices.memory.min_shard_index_buffer_size` and
`indices.memory.max_shard_index_buffer_size` have been removed as
Elasticsearch now allows any one shard to use  amount of heap as long as the
total indexing buffer heap used across all shards is below the node's
`indices.memory.index_buffer_size` (defaults to 10% of the JVM heap).

==== Removed es.max-open-files

Setting the system property es.max-open-files to true to get
Elasticsearch to print the number of maximum open files for the
Elasticsearch process has been removed. This same information can be
obtained from the <<cluster-nodes-info>> API, and a warning is logged
on startup if it is set too low.

==== Removed es.netty.gathering

Disabling Netty from using NIO gathering could be done via the escape
hatch of setting the system property "es.netty.gathering" to "false".
Time has proven enabling gathering by default is a non-issue and this
non-documented setting has been removed.

==== Removed es.useLinkedTransferQueue

The system property `es.useLinkedTransferQueue` could be used to
control the queue implementation used in the cluster service and the
handling of ping responses during discovery. This was an undocumented
setting and has been removed.

==== Cache concurrency level settings removed

Two cache concurrency level settings
`indices.requests.cache.concurrency_level` and
`indices.fielddata.cache.concurrency_level` because they no longer apply to
the cache implementation used for the request cache and the field data cache.