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 conventions Description

Syntax conventions	Description
UPPERCASE	Literal keyword.
Lowercase	Not literal.
`<Italics>`	Variable value. Replace with a valid option or user-defined value.
`[ ]`	Optional. Square brackets ( `[ ]` ) surround optional command arguments. Do not type the square brackets.
`( )`	Group. Parentheses ( `( )` ) identify a group to choose from. Do not type the parentheses.
`\|`	Or. A vertical bar ( `\|` ) separates alternative elements. Type any one of the elements. Do not type the vertical bar.
`...`	Repeatable. An ellipsis ( `...` ) indicates that you can repeat the syntax element as often as required.
`'<Literal string>'`	Single quotation ( `'` ) marks must surround literal strings in CQL statements. Use single quotation marks to preserve upper case.
`{ <key>:<value> }`	Map collection. Braces ( `{ }` ) enclose map collections or key value pairs. A colon separates the key and the value.
`<<datatype1>,<datatype2>>`	Set, list, map, or tuple. Angle brackets ( `< >` ) enclose data types in a set, list, map, or tuple. Separate the data types with a comma.
`cql_statement;`	End CQL statement. A semicolon ( `;` ) terminates all CQL statements.
`[ -- ]`	Separate the command line options from the command arguments with two hyphens ( `--` ). This syntax is useful when arguments might be mistaken for command line options.
`' <<schema> ... </schema> >'`	Search CQL only: Single quotation marks ( `'` ) surround an entire XML schema declaration.
`@<xml_entity>='<xml_entity_type>'`	Search CQL only: Identify the entity and literal value to overwrite the XML element in the schema and solrconfig files.

UPPERCASE

Literal keyword.

Lowercase

Not literal.

<Italics>

Variable value. Replace with a valid option or user-defined value.

[ ]

Optional. Square brackets ( [ ] ) surround optional command arguments. Do not type the square brackets.

( )

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

|

Or. A vertical bar ( | ) separates alternative elements. Type any one of the elements. Do not type the vertical bar.

...

Repeatable. An ellipsis ( ... ) indicates that you can repeat the syntax element as often as required.

'<Literal string>'

Single quotation ( ' ) marks must surround literal strings in CQL statements. Use single quotation marks to preserve upper case.

{ <key>:<value> }

Map collection. Braces ( { } ) enclose map collections or key value pairs. A colon separates the key and the value.

<<datatype1>,<datatype2>>

Set, list, map, or tuple. Angle brackets ( < > ) enclose data types in a set, list, map, or tuple. Separate the data types with a comma.

cql_statement;

End CQL statement. A semicolon ( ; ) terminates all CQL statements.

[ -- ]

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

' <<schema> ... </schema> >'

Search CQL only: Single quotation marks ( ' ) surround an entire XML schema declaration.

@<xml_entity>='<xml_entity_type>'

Search CQL only: Identify the entity and literal value to overwrite the XML element in the schema and solrconfig files.

Definition

The short- and long-form options are comma-separated.

Connection options

-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.

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

Definition

Connection options

Command arguments

Examples

Get failure detection information for the nodes in a cluster

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