nodetool setlogginglevel¶

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

Synopsis¶

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

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