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 |
---|---|
UPPERCASE |
Literal keyword. |
Lowercase |
Not literal. |
|
Variable value. Replace with a valid option or user-defined value. |
|
Optional.
Square brackets ( |
|
Group.
Parentheses ( |
|
Or.
A vertical bar ( |
|
Repeatable.
An ellipsis ( |
|
Single quotation ( |
|
Map collection.
Braces ( |
|
Set, list, map, or tuple.
Angle brackets ( |
|
End CQL statement.
A semicolon ( |
|
Separate the command line options from the command arguments with two hyphens ( |
|
Search CQL only: Single quotation marks ( |
|
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.
Command arguments
This command takes no arguments.
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 node10.101.02.110
is0.21788652
. 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 aphi
value of4.52288617
. This value suggests that the node might be experiencing issues. While still below the threshold, an elevatedphi
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 aphi
value of51.71286825
. Because thisphi
value exceeds the threshold of8
, it strongly suggests that the node is down or unreachable. Highphi
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