nodetool failuredetector

Returns the failure detector information for the cluster.

A Phi Accrual Failure Detector generates a phi value (φ) for each node in a cluster. The detector assesses node health dynamically by monitoring networking conditions and using statistical analysis to measure the heartbeat intervals for each node. Using this analysis, the failure detector algorithm calculates a continuous measure of suspicion about the current state of each node.

DSE compares the phi value for each node against a configurable threshold called the phi_convict_threshold, which is commonly set to 8.

If the phi value shown in the output is greater than the phi_convict_threshold setting in the cassandra.yaml file, the node is considered down.

Synopsis

nodetool [<connection_options>] failuredetector

Syntax legend

Syntax conventions Description

Syntax conventions	Description
Italic, bold, or `< >`	Syntax diagrams and code samples use one or more of these styles to mark placeholders for variable values. Replace placeholders with a valid option or your own user-defined value. In CQL statements, angle brackets are required to enclose data types in a set, list, map, or tuple. Separate the data types with a comma. For example: `<datatype2` In Search CQL statements, angle brackets are used to identify the entity and literal value to overwrite the XML element in the schema and `solrconfig` files, such as `@<xml_entity>='<xml_entity_type>'`.
`[ ]`	Square brackets surround optional command arguments. Do not type the square brackets.
`( )`	Parentheses identify a group to choose from. Do not type the parentheses.
`\|`	A pipe separates alternative elements. Type any one of the elements. Do not type the pipe.
`...`	Indicates that you can repeat the syntax element as often as required.
`'`	Single quotation marks must surround literal strings in CQL statements. Use single quotation marks to preserve upper case. + For Search CQL only: Single quotation marks surround an entire XML schema declaration, such as `'<<schema> ... </schema>>'`
`{ }`	Map collection. Curly braces enclose maps (`{ <key_datatype>:<value_datatype> }`) or key value pairs (`{ <key>:<value> }`). A colon separates the key and the value.
`;`	Ends a CQL statement.
`--`	Separate command line options from command arguments with two hyphens. This syntax is useful when arguments might be mistaken for command line options.

Italic, bold, or < >

Syntax diagrams and code samples use one or more of these styles to mark placeholders for variable values. Replace placeholders with a valid option or your own user-defined value.

In CQL statements, angle brackets are required to enclose data types in a set, list, map, or tuple. Separate the data types with a comma. For example: <datatype2

In Search CQL statements, angle brackets are used to identify the entity and literal value to overwrite the XML element in the schema and solrconfig files, such as @<xml_entity>='<xml_entity_type>'.

[ ]

Square brackets surround optional command arguments. Do not type the square brackets.

( )

Parentheses identify a group to choose from. Do not type the parentheses.

|

A pipe separates alternative elements. Type any one of the elements. Do not type the pipe.

...

Indicates that you can repeat the syntax element as often as required.

'

Single quotation marks must surround literal strings in CQL statements. Use single quotation marks to preserve upper case. + For Search CQL only: Single quotation marks surround an entire XML schema declaration, such as '<<schema> ... </schema>>'

{ }

Map collection. Curly braces enclose maps ({ <key_datatype>:<value_datatype> }) or key value pairs ({ <key>:<value> }). A colon separates the key and the value.

;

Ends a CQL statement.

--

Separate command line options from command arguments with two hyphens. This syntax is useful when arguments might be mistaken for command line options.

Options

If an option has a short and long form, both forms are given, separated by a comma.

-h, --host hostname: The hostname or IP address of a remote node or nodes. When omitted, the default is the local machine.
-p, --port jmx_port: The JMX port number.
-pw, --password jmxpassword: The JMX password for authenticating with secure JMX. If a password is not provided, you are prompted to enter one.
-pwf, --password-file jmx_password_filepath: The filepath to the file that stores JMX authentication credentials.
-u, --username jmx_username: The username for authenticating with secure JMX.

Examples

Get failure detection information for the nodes in a cluster

In the following output example, the phi value provides an indication of the health of each node in the cluster. The example assumes that the phi_convict_threshold is set to the default setting of 8.

The phi value for node 10.101.02.110 is 0.21788652. This value suggests that the node is up and healthy, with no sign of network or heartbeat delays.
The second node, 10.101.02.111, has a phi value of 4.52288617. This value suggests that the node might be experiencing issues. While still below the threshold, an elevated phi value can be an early sign of delayed heartbeat responses caused by network latency, intermittent packet loss, or node slowness.
The third node, 10.101.02.112, has a phi value of 51.71286825. Because this phi value exceeds the threshold of 8, it strongly suggests that the node is down or unreachable. High phi values result from a complete node failure, a severe network partition, or extreme slowness preventing the node from responding.

nodetool failuredetector

Endpoint             Phi
/10.101.02.110,      0.21788652
/10.101.02.111,      4.52288617
/10.101.02.112,      51.71286825

nodetool failuredetector

Synopsis

Options

Examples

Get failure detection information for the nodes in a cluster

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