112 lines
4.0 KiB
Plaintext
112 lines
4.0 KiB
Plaintext
[[misc-cluster]]
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=== Miscellaneous cluster settings
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[[cluster-read-only]]
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==== Metadata
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An entire cluster may be set to read-only with the following _dynamic_ setting:
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`cluster.blocks.read_only`::
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Make the whole cluster read only (indices do not accept write
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operations), metadata is not allowed to be modified (create or delete
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indices).
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`cluster.blocks.read_only_allow_delete`::
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Identical to `cluster.blocks.read_only` but allows to delete indices
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to free up resources.
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WARNING: Don't rely on this setting to prevent changes to your cluster. Any
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user with access to the <<cluster-update-settings,cluster-update-settings>>
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API can make the cluster read-write again.
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[[user-defined-data]]
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==== User Defined Cluster Metadata
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User-defined metadata can be stored and retrieved using the Cluster Settings API.
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This can be used to store arbitrary, infrequently-changing data about the cluster
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without the need to create an index to store it. This data may be stored using
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any key prefixed with `cluster.metadata.`. For example, to store the email
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address of the administrator of a cluster under the key `cluster.metadata.administrator`,
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issue this request:
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[source,js]
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-------------------------------
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PUT /_cluster/settings
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{
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"persistent": {
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"cluster.metadata.administrator": "sysadmin@example.com"
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}
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}
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-------------------------------
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// CONSOLE
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IMPORTANT: User-defined cluster metadata is not intended to store sensitive or
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confidential information. Any information stored in user-defined cluster
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metadata will be viewable by anyone with access to the
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<<cluster-get-settings,Cluster Get Settings>> API, and is recorded in the
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{es} logs.
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[[cluster-max-tombstones]]
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==== Index Tombstones
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The cluster state maintains index tombstones to explicitly denote indices that
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have been deleted. The number of tombstones maintained in the cluster state is
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controlled by the following property, which cannot be updated dynamically:
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`cluster.indices.tombstones.size`::
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Index tombstones prevent nodes that are not part of the cluster when a delete
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occurs from joining the cluster and reimporting the index as though the delete
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was never issued. To keep the cluster state from growing huge we only keep the
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last `cluster.indices.tombstones.size` deletes, which defaults to 500. You can
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increase it if you expect nodes to be absent from the cluster and miss more
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than 500 deletes. We think that is rare, thus the default. Tombstones don't take
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up much space, but we also think that a number like 50,000 is probably too big.
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[[cluster-logger]]
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==== Logger
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The settings which control logging can be updated dynamically with the
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`logger.` prefix. For instance, to increase the logging level of the
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`indices.recovery` module to `DEBUG`, issue this request:
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[source,js]
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-------------------------------
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PUT /_cluster/settings
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{
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"transient": {
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"logger.org.elasticsearch.indices.recovery": "DEBUG"
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}
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}
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-------------------------------
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// CONSOLE
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[[persistent-tasks-allocation]]
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==== Persistent Tasks Allocations
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Plugins can create a kind of tasks called persistent tasks. Those tasks are
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usually long-live tasks and are stored in the cluster state, allowing the
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tasks to be revived after a full cluster restart.
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Every time a persistent task is created, the master nodes takes care of
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assigning the task to a node of the cluster, and the assigned node will then
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pick up the task and execute it locally. The process of assigning persistent
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tasks to nodes is controlled by the following property, which can be updated
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dynamically:
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`cluster.persistent_tasks.allocation.enable`::
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+
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--
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Enable or disable allocation for persistent tasks:
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* `all` - (default) Allows persistent tasks to be assigned to nodes
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* `none` - No allocations are allowed for any type of persistent task
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This setting does not affect the persistent tasks that are already being executed.
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Only newly created persistent tasks, or tasks that must be reassigned (after a node
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left the cluster, for example), are impacted by this setting.
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-- |