diff --git a/docs/reference/modules/discovery/publishing.asciidoc b/docs/reference/modules/discovery/publishing.asciidoc index af664585085c2..c4d75f3320fba 100644 --- a/docs/reference/modules/discovery/publishing.asciidoc +++ b/docs/reference/modules/discovery/publishing.asciidoc @@ -58,3 +58,16 @@ speed of the storage on each master-eligible node, as well as the reliability and latency of the network interconnections between all nodes in the cluster. You must therefore ensure that the storage and networking available to the nodes in your cluster are good enough to meet your performance goals. + +[[dangling-index]] +==== Dangling indices + +When a node joins the cluster, if it finds any shards stored in its local +data directory that do not already exist in the cluster state, it will consider +those shards to belong to a "dangling" index. You can list, import or +delete dangling indices using the <>. + +NOTE: The API cannot offer any guarantees as to whether the imported data +truly represents the latest state of the data when the index was still part +of the cluster. \ No newline at end of file diff --git a/docs/reference/modules/gateway.asciidoc b/docs/reference/modules/gateway.asciidoc index bf7e6de64f093..9da5fddb6626c 100644 --- a/docs/reference/modules/gateway.asciidoc +++ b/docs/reference/modules/gateway.asciidoc @@ -1,6 +1,7 @@ [[modules-gateway]] === Local gateway settings +[[dangling-indices]] The local gateway stores the cluster state and shard data across full cluster restarts. diff --git a/docs/reference/modules/network.asciidoc b/docs/reference/modules/network.asciidoc index 1e4c5a21d386c..5095d73058d75 100644 --- a/docs/reference/modules/network.asciidoc +++ b/docs/reference/modules/network.asciidoc @@ -286,3 +286,22 @@ include::remote-cluster-network.asciidoc[] include::network/tracers.asciidoc[] include::network/threading.asciidoc[] + +[[tcp-readiness-port]] +==== TCP readiness port + +preview::[] + +If configured, a node can open a TCP port when the node is in a ready state. A node is deemed +ready when it has successfully joined a cluster. In a single node configuration, the node is +said to be ready, when it's able to accept requests. + +To enable the readiness TCP port, use the `readiness.port` setting. The readiness service will bind to +all host addresses. + +If the node leaves the cluster, or the <> is used to mark the node +for shutdown, the readiness port is immediately closed. + +A successful connection to the readiness TCP port signals that the {es} node is ready. When a client +connects to the readiness port, the server simply terminates the socket connection. No data is sent back +to the client. If a client cannot connect to the readiness port, the node is not ready. \ No newline at end of file diff --git a/docs/reference/modules/node.asciidoc b/docs/reference/modules/node.asciidoc index 022e8b5d1e2fe..524fefb492354 100644 --- a/docs/reference/modules/node.asciidoc +++ b/docs/reference/modules/node.asciidoc @@ -37,6 +37,8 @@ set `node.roles`, the node is assigned the following roles: * `remote_cluster_client` * `transform` +[[coordinating-only-node]]If you leave `node.roles` unset, then the node is considered to be a <>. + [IMPORTANT] ==== If you set `node.roles`, ensure you specify every node role your cluster needs. diff --git a/docs/reference/node-roles.asciidoc b/docs/reference/node-roles.asciidoc new file mode 100644 index 0000000000000..296c76e6dba9b --- /dev/null +++ b/docs/reference/node-roles.asciidoc @@ -0,0 +1,437 @@ +[[node-roles-overview]] +== Node roles + +Any time that you start an instance of {es}, you are starting a _node_. A +collection of connected nodes is called a <>. If you +are running a single node of {es}, then you have a cluster of one node. All nodes know about all the other nodes in the cluster and can forward client +requests to the appropriate node. + +Each node performs one or more roles. Roles control the behavior of the node in the cluster. + +[discrete] +[[set-node-roles]] +=== Set node roles + +You define a node's roles by setting `node.roles` in <>. If you set `node.roles`, the node is only assigned the roles you specify. If you don't set `node.roles`, the node is assigned the following roles: + +* `master` +* `data` +* `data_content` +* `data_hot` +* `data_warm` +* `data_cold` +* `data_frozen` +* `ingest` +* `ml` +* `remote_cluster_client` +* `transform` + +[IMPORTANT] +==== +If you set `node.roles`, ensure you specify every node role your cluster needs. +Every cluster requires the following node roles: + +* `master` +* {blank} ++ +-- +`data_content` and `data_hot` + +OR + +`data` +-- + +Some {stack} features also require specific node roles: + +- {ccs-cap} and {ccr} require the `remote_cluster_client` role. +- {stack-monitor-app} and ingest pipelines require the `ingest` role. +- {fleet}, the {security-app}, and {transforms} require the `transform` role. + The `remote_cluster_client` role is also required to use {ccs} with these + features. +- {ml-cap} features, such as {anomaly-detect}, require the `ml` role. +==== + +As the cluster grows and in particular if you have large {ml} jobs or +{ctransforms}, consider separating dedicated master-eligible nodes from +dedicated data nodes, {ml} nodes, and {transform} nodes. + +[discrete] +[[change-node-role]] +=== Change the role of a node + +Each data node maintains the following data on disk: + +* the shard data for every shard allocated to that node, +* the index metadata corresponding with every shard allocated to that node, and +* the cluster-wide metadata, such as settings and index templates. + +Similarly, each master-eligible node maintains the following data on disk: + +* the index metadata for every index in the cluster, and +* the cluster-wide metadata, such as settings and index templates. + +Each node checks the contents of its data path at startup. If it discovers +unexpected data then it will refuse to start. This is to avoid importing +unwanted <> which can lead +to a red cluster health. To be more precise, nodes without the `data` role will +refuse to start if they find any shard data on disk at startup, and nodes +without both the `master` and `data` roles will refuse to start if they have any +index metadata on disk at startup. + +It is possible to change the roles of a node by adjusting its +`elasticsearch.yml` file and restarting it. This is known as _repurposing_ a +node. In order to satisfy the checks for unexpected data described above, you +must perform some extra steps to prepare a node for repurposing when starting +the node without the `data` or `master` roles. + +* If you want to repurpose a data node by removing the `data` role then you + should first use an <> to safely + migrate all the shard data onto other nodes in the cluster. + +* If you want to repurpose a node to have neither the `data` nor `master` roles + then it is simplest to start a brand-new node with an empty data path and the + desired roles. You may find it safest to use an + <> to migrate the shard data elsewhere + in the cluster first. + +If it is not possible to follow these extra steps then you may be able to use +the <> tool to delete any +excess data that prevents a node from starting. + +[discrete] +[[node-roles-list]] +=== Available node roles + +The following is a list of the roles that a node can perform in a cluster. A node can have one or more roles. + +* <> (`master`): A node that is eligible to be +<>, which controls the cluster. + +* <> (`data`, `data_content`, `data_hot`, `data_warm`, `data_cold`, `data_frozen`): A node that has one of several data roles. Data nodes hold data and perform data related operations such as CRUD, search, and aggregations. You might use multiple data roles in a cluster so you can implement <>. + +* <> (`ingest`): Ingest nodes are able to apply an <> to a document in order to transform and enrich the document before indexing. With a heavy ingest load, it makes sense to use dedicated ingest nodes and to not include the `ingest` role from nodes that have the `master` or `data` roles. + +* <> (`remote_cluster_client`): A node that is eligible to act as a remote client. + +* <> (`ml`): A node that can run {ml-features}. If you want to use {ml-features}, there must be at least one {ml} node in your cluster. For more information, see <> and {ml-docs}/index.html[Machine learning in the {stack}]. + +* <> (`transform`): A node that can perform {transforms}. If you want to use {transforms}, there must be at least one {transform} node in your cluster. For more information, see <> and <>. + +[NOTE] +[[coordinating-node]] +.Coordinating node +=============================================== + +Requests like search requests or bulk-indexing requests may involve data held +on different data nodes. A search request, for example, is executed in two +phases which are coordinated by the node which receives the client request -- +the _coordinating node_. + +In the _scatter_ phase, the coordinating node forwards the request to the data +nodes which hold the data. Each data node executes the request locally and +returns its results to the coordinating node. In the _gather_ phase, the +coordinating node reduces each data node's results into a single global +result set. + +Every node is implicitly a coordinating node. This means that a node that has +an explicit empty list of roles in the `node.roles` setting will only act as a coordinating +node, which cannot be disabled. As a result, such a node needs to have enough +memory and CPU in order to deal with the gather phase. + +=============================================== + +[discrete] + +[[master-node-role]] +==== Master-eligible node + +The master node is responsible for lightweight cluster-wide actions such as +creating or deleting an index, tracking which nodes are part of the cluster, +and deciding which shards to allocate to which nodes. It is important for +cluster health to have a stable master node. + +Any master-eligible node that is not a <> may +be elected to become the master node by the <>. + +IMPORTANT: Master nodes must have a `path.data` directory whose contents +persist across restarts, just like data nodes, because this is where the +cluster metadata is stored. The cluster metadata describes how to read the data +stored on the data nodes, so if it is lost then the data stored on the data +nodes cannot be read. + +[discrete] +[[dedicated-master-node]] +===== Dedicated master-eligible node + +It is important for the health of the cluster that the elected master node has +the resources it needs to fulfill its responsibilities. If the elected master +node is overloaded with other tasks then the cluster will not operate well. The +most reliable way to avoid overloading the master with other tasks is to +configure all the master-eligible nodes to be _dedicated master-eligible nodes_ +which only have the `master` role, allowing them to focus on managing the +cluster. Master-eligible nodes will still also behave as +<> that route requests from clients to +the other nodes in the cluster, but you should _not_ use dedicated master nodes +for this purpose. + +A small or lightly-loaded cluster may operate well if its master-eligible nodes +have other roles and responsibilities, but once your cluster comprises more +than a handful of nodes it usually makes sense to use dedicated master-eligible +nodes. + +To create a dedicated master-eligible node, set: + +[source,yaml] +------------------- +node.roles: [ master ] +------------------- + +[discrete] +[[voting-only-node]] +===== Voting-only master-eligible node + +A voting-only master-eligible node is a node that participates in +<> but which will not act as the cluster's +elected master node. In particular, a voting-only node can serve as a tiebreaker +in elections. + +It may seem confusing to use the term "master-eligible" to describe a +voting-only node since such a node is not actually eligible to become the master +at all. This terminology is an unfortunate consequence of history: +master-eligible nodes are those nodes that participate in elections and perform +certain tasks during cluster state publications, and voting-only nodes have the +same responsibilities even if they can never become the elected master. + +To configure a master-eligible node as a voting-only node, include `master` and +`voting_only` in the list of roles. For example to create a voting-only data +node: + +[source,yaml] +------------------- +node.roles: [ data, master, voting_only ] +------------------- + +IMPORTANT: Only nodes with the `master` role can be marked as having the +`voting_only` role. + +High availability (HA) clusters require at least three master-eligible nodes, at +least two of which are not voting-only nodes. Such a cluster will be able to +elect a master node even if one of the nodes fails. + +Voting-only master-eligible nodes may also fill other roles in your cluster. +For instance, a node may be both a data node and a voting-only master-eligible +node. A _dedicated_ voting-only master-eligible nodes is a voting-only +master-eligible node that fills no other roles in the cluster. To create a +dedicated voting-only master-eligible node, set: + +[source,yaml] +------------------- +node.roles: [ master, voting_only ] +------------------- + +Since dedicated voting-only nodes never act as the cluster's elected master, +they may require less heap and a less powerful CPU than the true master nodes. +However all master-eligible nodes, including voting-only nodes, are on the +critical path for <>. Cluster state updates are usually independent of +performance-critical workloads such as indexing or searches, but they are +involved in management activities such as index creation and rollover, mapping +updates, and recovery after a failure. The performance characteristics of these +activities are a function of the speed of the storage on each master-eligible +node, as well as the reliability and latency of the network interconnections +between the elected master node and the other nodes in the cluster. You must +therefore ensure that the storage and networking available to the nodes in your +cluster are good enough to meet your performance goals. + +[discrete] +[[data-node-role]] +==== Data nodes + +Data nodes hold the shards that contain the documents you have indexed. Data +nodes handle data related operations like CRUD, search, and aggregations. +These operations are I/O-, memory-, and CPU-intensive. It is important to +monitor these resources and to add more data nodes if they are overloaded. + +The main benefit of having dedicated data nodes is the separation of the master +and data roles. + +In a multi-tier deployment architecture, you use specialized data roles to +assign data nodes to specific tiers: `data_content`,`data_hot`, `data_warm`, +`data_cold`, or `data_frozen`. A node can belong to multiple tiers. + +If you want to include a node in all tiers, or if your cluster does not use multiple tiers, then you can use the generic `data` role. + +include::{es-ref-dir}/how-to/shard-limits.asciidoc[] + +WARNING: If you assign a node to a specific tier using a specialized data role, then you shouldn't also assign it the generic `data` role. The generic `data` role takes precedence over specialized data roles. + +[discrete] +[[generic-data-node]] +===== Generic data node + +Generic data nodes are included in all content tiers. A node with a generic `data` role can fill any of the specialized data node roles. + +To create a dedicated generic data node, set: +[source,yaml] +---- +node.roles: [ data ] +---- + +[discrete] +[[data-content-node]] +===== Content data node + +Content data nodes are part of the content tier. +include::{es-ref-dir}/datatiers.asciidoc[tag=content-tier] + +To create a dedicated content node, set: +[source,yaml] +---- +node.roles: [ data_content ] +---- + +[discrete] +[[data-hot-node]] +===== Hot data node + +Hot data nodes are part of the hot tier. +include::{es-ref-dir}/datatiers.asciidoc[tag=hot-tier] + +To create a dedicated hot node, set: +[source,yaml] +---- +node.roles: [ data_hot ] +---- + +[discrete] +[[data-warm-node]] +===== Warm data node + +Warm data nodes are part of the warm tier. +include::{es-ref-dir}/datatiers.asciidoc[tag=warm-tier] + +To create a dedicated warm node, set: +[source,yaml] +---- +node.roles: [ data_warm ] +---- + +[discrete] +[[data-cold-node]] +===== Cold data node + +Cold data nodes are part of the cold tier. +include::{es-ref-dir}/datatiers.asciidoc[tag=cold-tier] + +To create a dedicated cold node, set: +[source,yaml] +---- +node.roles: [ data_cold ] +---- + +[discrete] +[[data-frozen-node]] +===== Frozen data node + +Frozen data nodes are part of the frozen tier. +include::{es-ref-dir}/datatiers.asciidoc[tag=frozen-tier] + +To create a dedicated frozen node, set: +[source,yaml] +---- +node.roles: [ data_frozen ] +---- + +[discrete] +[[node-ingest-node]] +==== Ingest node + +Ingest nodes can execute pre-processing pipelines, composed of one or more +ingest processors. Depending on the type of operations performed by the ingest +processors and the required resources, it may make sense to have dedicated +ingest nodes, that will only perform this specific task. + +To create a dedicated ingest node, set: + +[source,yaml] +---- +node.roles: [ ingest ] +---- + +[discrete] +[[coordinating-only-node-role]] +==== Coordinating only node + +If you take away the ability to be able to handle master duties, to hold data, +and pre-process documents, then you are left with a _coordinating_ node that +can only route requests, handle the search reduce phase, and distribute bulk +indexing. Essentially, coordinating only nodes behave as smart load balancers. + +Coordinating only nodes can benefit large clusters by offloading the +coordinating node role from data and master-eligible nodes. They join the +cluster and receive the full <>, like every other +node, and they use the cluster state to route requests directly to the +appropriate place(s). + +WARNING: Adding too many coordinating only nodes to a cluster can increase the +burden on the entire cluster because the elected master node must await +acknowledgement of cluster state updates from every node! The benefit of +coordinating only nodes should not be overstated -- data nodes can happily +serve the same purpose. + +To create a dedicated coordinating node, set: + +[source,yaml] +---- +node.roles: [ ] +---- + +[discrete] +[[remote-node]] +==== Remote-eligible node + +A remote-eligible node acts as a cross-cluster client and connects to +<>. Once connected, you can search +remote clusters using <>. You can also sync +data between clusters using <>. + +[source,yaml] +---- +node.roles: [ remote_cluster_client ] +---- + +[discrete] +[[ml-node-role]] +==== [xpack]#Machine learning node# + +{ml-cap} nodes run jobs and handle {ml} API requests. For more information, see +<>. + +To create a dedicated {ml} node, set: + +[source,yaml] +---- +node.roles: [ ml, remote_cluster_client] +---- + +The `remote_cluster_client` role is optional but strongly recommended. +Otherwise, {ccs} fails when used in {ml} jobs or {dfeeds}. If you use {ccs} in +your {anomaly-jobs}, the `remote_cluster_client` role is also required on all +master-eligible nodes. Otherwise, the {dfeed} cannot start. See <>. + +[discrete] +[[transform-node-role]] +==== [xpack]#{transform-cap} node# + +{transform-cap} nodes run {transforms} and handle {transform} API requests. For +more information, see <>. + +To create a dedicated {transform} node, set: + +[source,yaml] +---- +node.roles: [ transform, remote_cluster_client ] +---- + +The `remote_cluster_client` role is optional but strongly recommended. +Otherwise, {ccs} fails when used in {transforms}. See <>. \ No newline at end of file diff --git a/docs/reference/setup/advanced-configuration.asciidoc b/docs/reference/setup/advanced-configuration.asciidoc index 2a7ccc56742de..32399b5fa7557 100644 --- a/docs/reference/setup/advanced-configuration.asciidoc +++ b/docs/reference/setup/advanced-configuration.asciidoc @@ -21,6 +21,7 @@ Where you put the JVM options files depends on the type of installation: * Docker: Bind mount custom JVM options files into `/usr/share/elasticsearch/config/jvm.options.d/`. +[[readiness-tcp-port]] NOTE: Do not modify the root `jvm.options` file. Use files in `jvm.options.d/` instead. [[jvm-options-syntax]] @@ -155,23 +156,11 @@ options. We do not recommend using `ES_JAVA_OPTS` in production. NOTE: If you are running {es} as a Windows service, you can change the heap size using the service manager. See <>. -[[readiness-tcp-port]] -===== Enable the Elasticsearch TCP readiness port - -preview::[] - -If configured, a node can open a TCP port when the node is in a ready state. A node is deemed -ready when it has successfully joined a cluster. In a single node configuration, the node is -said to be ready, when it's able to accept requests. - -To enable the readiness TCP port, use the `readiness.port` setting. The readiness service will bind to -all host addresses. - -If the node leaves the cluster, or the <> is used to mark the node -for shutdown, the readiness port is immediately closed. - -A successful connection to the readiness TCP port signals that the {es} node is ready. When a client -connects to the readiness port, the server simply terminates the socket connection. No data is sent back -to the client. If a client cannot connect to the readiness port, the node is not ready. +[[heap-dump-path-setting]] +include::important-settings/heap-dump-path.asciidoc[leveloffset=-1] +[[gc-logging]] +include::important-settings/gc-logging.asciidoc[leveloffset=-1] +[[error-file-path]] +include::important-settings/error-file.asciidoc[leveloffset=-1] \ No newline at end of file diff --git a/docs/reference/setup/important-settings.asciidoc b/docs/reference/setup/important-settings.asciidoc index 03c891af70743..737c2c4556d54 100644 --- a/docs/reference/setup/important-settings.asciidoc +++ b/docs/reference/setup/important-settings.asciidoc @@ -31,6 +31,7 @@ include::important-settings/discovery-settings.asciidoc[] include::important-settings/heap-size.asciidoc[] +[[heap-dump-path]] include::important-settings/heap-dump-path.asciidoc[] include::important-settings/gc-logging.asciidoc[]