Discovery and cluster formation are affected by the following settings:
-
discovery.seed_hosts -
Provides a list of master-eligible nodes in the cluster. Each value has the
format
host:portorhost, whereportdefaults to the settingtransport.profiles.default.port. Note that IPv6 hosts must be bracketed. The default value is["127.0.0.1", "[::1]"]. Seediscovery.seed_hosts. This setting was previously known asdiscovery.zen.ping.unicast.hosts. Its old name is deprecated but continues to work in order to preserve backwards compatibility. Support for the old name will be removed in a future version. -
discovery.seed_providers -
Specifies which types of seed hosts provider
to use to obtain the addresses of the seed nodes used to start the
discovery process. By default, it is the
settings-based seed hosts provider. This
setting was previously known as
discovery.zen.hosts_provider. Its old name is deprecated but continues to work in order to preserve backwards compatibility. Support for the old name will be removed in a future version. -
cluster.initial_master_nodes -
Sets a list of the node names or transport addresses of the
initial set of master-eligible nodes in a brand-new cluster. By default
this list is empty, meaning that this node expects to join a cluster that
has already been bootstrapped. See
cluster.initial_master_nodes.
Expert settings
Discovery and cluster formation are also affected by the following expert-level settings, although it is not recommended to change any of these from their default values.
[WARNING] If you adjust these settings then your cluster may not form correctly or may become unstable or intolerant of certain failures.
-
discovery.cluster_formation_warning_timeout -
Sets how long a node will try to form a cluster before logging a warning
that the cluster did not form. Defaults to
10s. If a cluster has not formed afterdiscovery.cluster_formation_warning_timeouthas elapsed then the node will log a warning message that starts with the phrasemaster not discoveredwhich describes the current state of the discovery process. -
discovery.find_peers_interval -
Sets how long a node will wait before attempting another discovery round.
Defaults to
1s. -
discovery.probe.connect_timeout -
Sets how long to wait when attempting to connect to each address. Defaults
to
3s. -
discovery.probe.handshake_timeout -
Sets how long to wait when attempting to identify the remote node via a
handshake. Defaults to
1s. -
discovery.request_peers_timeout -
Sets how long a node will wait after asking its peers again before
considering the request to have failed. Defaults to
3s. -
discovery.seed_resolver.max_concurrent_resolvers -
Specifies how many concurrent DNS lookups to perform when resolving the
addresses of seed nodes. Defaults to
10. This setting was previously known asdiscovery.zen.ping.unicast.concurrent_connects. Its old name is deprecated but continues to work in order to preserve backwards compatibility. Support for the old name will be removed in a future version. -
discovery.seed_resolver.timeout -
Specifies how long to wait for each DNS lookup performed when resolving the
addresses of seed nodes. Defaults to
5s. This setting was previously known asdiscovery.zen.ping.unicast.hosts.resolve_timeout. Its old name is deprecated but continues to work in order to preserve backwards compatibility. Support for the old name will be removed in a future version. -
cluster.auto_shrink_voting_configuration -
Controls whether the voting configuration
sheds departed nodes automatically, as long as it still contains at least 3
nodes. The default value is
true. If set tofalse, the voting configuration never shrinks automatically and you must remove departed nodes manually with the voting configuration exclusions API. -
cluster.election.back_off_time -
Sets the amount to increase the upper bound on the wait before an election
on each election failure. Note that this is linear backoff. This defaults
to
100ms. Changing this setting from the default may cause your cluster to fail to elect a master node. -
cluster.election.duration -
Sets how long each election is allowed to take before a node considers it
to have failed and schedules a retry. This defaults to
500ms. Changing this setting from the default may cause your cluster to fail to elect a master node. -
cluster.election.initial_timeout -
Sets the upper bound on how long a node will wait initially, or after the
elected master fails, before attempting its first election. This defaults
to
100ms. Changing this setting from the default may cause your cluster to fail to elect a master node. -
cluster.election.max_timeout -
Sets the maximum upper bound on how long a node will wait before attempting
an first election, so that an network partition that lasts for a long time
does not result in excessively sparse elections. This defaults to
10s. Changing this setting from the default may cause your cluster to fail to elect a master node. -
cluster.fault_detection.follower_check.interval -
Sets how long the elected master waits between follower checks to each
other node in the cluster. Defaults to
1s. Changing this setting from the default may cause your cluster to become unstable. -
cluster.fault_detection.follower_check.timeout -
Sets how long the elected master waits for a response to a follower check
before considering it to have failed. Defaults to
10s. Changing this setting from the default may cause your cluster to become unstable. -
cluster.fault_detection.follower_check.retry_count -
Sets how many consecutive follower check failures must occur to each node
before the elected master considers that node to be faulty and removes it
from the cluster. Defaults to
3. Changing this setting from the default may cause your cluster to become unstable. -
cluster.fault_detection.leader_check.interval -
Sets how long each node waits between checks of the elected master.
Defaults to
1s. Changing this setting from the default may cause your cluster to become unstable. -
cluster.fault_detection.leader_check.timeout -
Sets how long each node waits for a response to a leader check from the
elected master before considering it to have failed. Defaults to
10s. Changing this setting from the default may cause your cluster to become unstable. -
cluster.fault_detection.leader_check.retry_count -
Sets how many consecutive leader check failures must occur before a node
considers the elected master to be faulty and attempts to find or elect a
new master. Defaults to
3. Changing this setting from the default may cause your cluster to become unstable. -
cluster.follower_lag.timeout -
Sets how long the master node waits to receive acknowledgements for cluster
state updates from lagging nodes. The default value is
90s. If a node does not successfully apply the cluster state update within this period of time, it is considered to have failed and is removed from the cluster. See Publishing the cluster state. -
cluster.join.timeout -
Sets how long a node will wait after sending a request to join a cluster
before it considers the request to have failed and retries. Defaults to
60s. -
cluster.max_voting_config_exclusions -
Sets a limit on the number of voting configuration exclusions at any one
time. The default value is
10. See Adding and removing nodes. -
cluster.publish.timeout -
Sets how long the master node waits for each cluster state update to be
completely published to all nodes. The default value is
30s. See Publishing the cluster state. -
cluster.no_master_block Specifies which operations are rejected when there is no active master in a cluster. This setting has two valid values:
-
all - All operations on the node (both read and write operations) are rejected. This also applies for API cluster state read or write operations, like the get index settings, put mapping and cluster state API.
-
write - (default) Write operations are rejected. Read operations succeed, based on the last known cluster configuration. This situation may result in partial reads of stale data as this node may be isolated from the rest of the cluster.
-
The
cluster.no_master_blocksetting doesn’t apply to nodes-based APIs (for example, cluster stats, node info, and node stats APIs). Requests to these APIs are not be blocked and can run on any available node. - For the cluster to be fully operational, it must have an active master.
This setting replaces the
discovery.zen.no_master_blocksetting in earlier versions. Thediscovery.zen.no_master_blocksetting is ignored.-