nodetool setlogginglevel

Changes the logging level for a class or package at runtime.

Synopsis

nodetool [connection_options] setlogginglevel [<class|component>] [<level>]

See connection options for connection options.

Description

nodetool setlogginglevel dynamically changes the logging level for a specific Java class, package, or built-in component without restarting Cassandra. This is useful for debugging issues in production.

Non-Persistent Setting

This setting is applied at runtime only and does not persist across node restarts. After a restart, the logging levels revert to the configuration in logback.xml.

Reset All Loggers

Calling nodetool setlogginglevel with no arguments resets all logging levels to the initial configuration from logback.xml.

Arguments

Argument	Description
`class`	Fully qualified class name, package, or built-in component name. If omitted with level, resets all loggers
`level`	Log level: TRACE, DEBUG, INFO, WARN, ERROR, OFF. If omitted, resets the specified logger

Built-in Component Shortcuts

The command supports component shortcuts that map to predefined logger sets:

Component	Description	Mapped Loggers
`bootstrap`	Bootstrap operations	Bootstrap-related loggers
`compaction`	Compaction operations	`org.apache.cassandra.db.compaction`
`repair`	Repair operations	`org.apache.cassandra.repair`
`streaming`	Streaming operations	`org.apache.cassandra.streaming`
`cql`	CQL query handling	CQL transport loggers
`ring`	Ring/token management	Ring-related loggers

Log Levels

Level	Description
`TRACE`	Most verbose; detailed tracing information
`DEBUG`	Debugging information
`INFO`	Informational messages (default)
`WARN`	Warning messages
`ERROR`	Error messages only
`OFF`	Disable logging

Examples

Enable Debug for Compaction

nodetool setlogginglevel org.apache.cassandra.db.compaction DEBUG

Enable Debug for Gossip

nodetool setlogginglevel org.apache.cassandra.gms DEBUG

Enable Debug for Repair

nodetool setlogginglevel org.apache.cassandra.repair DEBUG

Enable Debug for All Cassandra Classes

nodetool setlogginglevel org.apache.cassandra DEBUG

Enable Trace for Specific Class

nodetool setlogginglevel org.apache.cassandra.db.compaction.CompactionManager TRACE

Disable Logging for Noisy Class

nodetool setlogginglevel org.apache.cassandra.transport.messages OFF

Reset to Default (INFO)

nodetool setlogginglevel org.apache.cassandra.db.compaction INFO

Reset All Loggers to Initial Configuration

# No arguments resets all loggers
nodetool setlogginglevel

Reset Specific Logger

# Omit level to reset a specific logger
nodetool setlogginglevel org.apache.cassandra.db.compaction

Using Component Shortcuts

# Enable DEBUG for compaction using component shortcut
nodetool setlogginglevel compaction DEBUG

# Enable DEBUG for repair
nodetool setlogginglevel repair DEBUG

# Enable DEBUG for streaming
nodetool setlogginglevel streaming DEBUG

Common Debug Targets

Compaction Issues

nodetool setlogginglevel org.apache.cassandra.db.compaction DEBUG

Repair Problems

nodetool setlogginglevel org.apache.cassandra.repair DEBUG
nodetool setlogginglevel org.apache.cassandra.streaming DEBUG

Gossip/Cluster Issues

nodetool setlogginglevel org.apache.cassandra.gms DEBUG
nodetool setlogginglevel org.apache.cassandra.net DEBUG

Read/Write Path

nodetool setlogginglevel org.apache.cassandra.db DEBUG
nodetool setlogginglevel org.apache.cassandra.service DEBUG

Authentication Issues

nodetool setlogginglevel org.apache.cassandra.auth DEBUG

CQL Protocol

nodetool setlogginglevel org.apache.cassandra.transport DEBUG

Hinted Handoff

nodetool setlogginglevel org.apache.cassandra.hints DEBUG

Viewing Changed Levels

nodetool getlogginglevels

Shows all loggers with non-default levels.

Workflow: Debug an Issue

# 1. Enable debug logging for relevant component
nodetool setlogginglevel org.apache.cassandra.db.compaction DEBUG

# 2. Reproduce the issue
nodetool compact my_keyspace my_table

# 3. Check logs
tail -f /var/log/cassandra/debug.log

# 4. Reset logging level
nodetool setlogginglevel org.apache.cassandra.db.compaction INFO

Log Output Location

Debug/trace logs typically go to:

/var/log/cassandra/debug.log

Check logback.xml for exact configuration.

Important Considerations

Performance Impact

DEBUG and TRACE levels generate significant log volume
May impact performance on busy clusters
May fill disk quickly
Always reset after debugging

Best Practices

Be specific - Target specific classes, not broad packages
Time-limited - Enable only for debugging duration
Monitor disk - Debug logs grow fast
Reset promptly - Return to INFO when done

Scripting Example

#!/bin/bash
# debug_compaction.sh - Enable debug, wait, then reset

DURATION=${1:-60}  # Default 60 seconds

echo "Enabling compaction debug logging for $DURATION seconds..."
nodetool setlogginglevel org.apache.cassandra.db.compaction DEBUG

sleep $DURATION

echo "Resetting to INFO..."
nodetool setlogginglevel org.apache.cassandra.db.compaction INFO

echo "Done. Check /var/log/cassandra/debug.log"

Command	Relationship
getlogginglevels	View current logging levels
info	Node information
compactionstats	Alternative to debug logs