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Configuring Application Logs

Service Logs​

Each Ozone service (Ozone Manager, Storage Container Manager, Datanode, S3 Gateway, and Recon) generates its own log file. These logs contain detailed information about the service’s operations, including errors and warnings.

By default, log files are stored in the $OZONE_LOG_DIR directory, which is usually set to the logs directory under the Ozone installation. The log file names are specific to each service, for example:

  • ozone-om-....log for Ozone Manager
  • ozone-scm-....log for Storage Container Manager
  • ozone-datanode-....log for Datanode

The logging behavior for each service is controlled by its log4j.properties file, located in the service’s $OZONE_CONF_DIR directory, usually etc/hadoop. You can modify this file to change the log level, logging outputs, and other logging parameters.

Datanode Container Logs​

In addition to the main service log, Datanode also generates container-specific logs that track container replica-level events. These logs record brief messages about container state changes (open, closing, closed, unhealthy), replication events, reconstruction, reconciliation, container moves, and other container lifecycle events.

Container logs are configured via dn-container-log4j2.properties and are stored as dn-container-${hostName}.log in the $OZONE_LOG_DIR directory.

Example​

2026-02-01 16:08:59,261 | INFO  | ID=2 | Index=0 | BCSID=0 | State=OPEN | Volume=/hadoop-ozone/datanode/data/hdds | DataChecksum=0 |
2026-02-03 12:49:36,139 | INFO  | ID=2 | Index=0 | BCSID=1172 | State=CLOSING | Volume=/hadoop-ozone/datanode/data/hdds | DataChecksum=0 |
2026-02-03 12:49:37,443 | INFO  | ID=2 | Index=0 | BCSID=1172 | State=CLOSED | Volume=/hadoop-ozone/datanode/data/hdds | DataChecksum=4117a7a2 |
2026-02-03 13:31:17,149 | INFO  | ID=2018 | Index=0 | BCSID=159 | State=CLOSING | Volume=/mnt/dummy_disk1/hadoop-ozone/datanode/data/hdds | DataChecksum=0 |
2026-02-03 13:31:17,205 | WARN  | ID=2018 | Index=0 | BCSID=159 | State=QUASI_CLOSED | Volume=/mnt/dummy_disk1/hadoop-ozone/datanode/data/hdds | DataChecksum=2a21d155 | Ratis group removed. Group id: group-82AA09A3DA8C |

Debugging​

You can increase the log verbosity for debugging purposes for both services and CLI tools.

Enabling Debug Logs for Services​

To enable debug logging for a service, you need to modify its log4j.properties file. Change the log level for the desired logger from INFO to DEBUG. For example, to enable debug logging for the Ozone Manager, you would edit its log4j.properties and change the following line:

rootLogger.level = info

to

rootLogger.level = debug

After saving the file and restarting the service, the service will start logging more detailed debug information.

Enabling Debug Logs for CLI Tools​

To enable debug logging for Ozone CLI tools (e.g., ozone sh volume create), you can set the OZONE_ROOT_LOGGER environment variable to debug:

export OZONE_ROOT_LOGGER=DEBUG,console
ozone sh volume create /vol1

Alternatively, you can use the --loglevel option with the Ozone command:

ozone --loglevel debug sh volume create /vol1