Inspect YugabyteDB logs

YugabyteDB has an extensive error-handling mechanism, with logging being one of its main components.

YugabyteDB base folder

The logs for each node are written to a subdirectory of the YugabyteDB yugabyte-data directory and may vary depending on your deployment, as follows:

• When you use yb-ctl to create local YugabyteDB clusters on a single host (for example, your computer), the default location for each node is /yugabyte-data/node-<node_nr>/. For a 3-node cluster, the yb-ctl utility creates three directories: node-1, node-2, node-3.
• For a multi-node cluster deployment to multiple hosts, the location where YugabyteDB disks are set up can vary (for example, /home/centos/, /mnt/, or another directory) on each node (host).
• When using the --fs_data_dirs flag with multiple directories, logs are saved in the first directory in the list.
• When using YugabyteDB Anywhere, logs are located in /home/yugabyte/{master,tserver}/logs. This is a symlink to the first directory in --fs_data_dirs list.
• When using the Docker container, logs are located in /root/var/logs inside the container.
• When using the yugabyted command-line interface to create the local YugabyteDB cluster, by default logs are located in ~/var/logs.

In this document, the YugabyteDB yugabyte-data directory is represented by <yugabyte-data-directory>.

YB-Master logs

The YB-Master service manages system metadata, such as namespaces (databases or keyspaces) and tables. It also handles Data Definition Language (DDL) statements such as CREATE TABLE, DROP TABLE, ALTER TABLE, KEYSPACE/TYPE. In addition, it manages users, permissions, and coordinate background operations, such as load balancing. You can access these logs as follows:

cd <yugabyte-data-directory>/disk1/yb-data/master/logs/

Logs are organized by error severity: FATAL, ERROR, WARNING, INFO.

YB-TServer logs

The YB-TServer service performs the actual input-output for end-user requests. It handles Data Manipulation Language (DML) statements such as INSERT, UPDATE, DELETE, and SELECT. You can access these logs as follows:

cd <yugabyte-data-directory>/disk1/yb-data/tserver/logs/

Logs are organized by error severity: FATAL, ERROR, WARNING, INFO.

Logs management

For YB-Master and YB-TServer, the log rotation size is controlled by the --max_log_size flag. For example, setting this flag to 256 limits each file to 256 MB. The default size is 1.8 GB.

For YSQL, there are additional postgres*log files that have daily-based and size-based log rotation. That is, a new log file is created every day or when a log reaches 10 MB in size.

For information on available configuration flags, see YB-Master logging flags and YB-TServer logging flags.

Log format

YB-Master and YB-TServer log messages follow this pattern:

Lmmdd hh:mm:ss.uuuuuu threadid file:line] msg

The fields are as follows:

• L: A single character, representing the log level (I for INFO, W for WARNING, E for ERROR, and F for FATAL).
• mm: Month (zero-padded; for example, May is 05).
• dd: Day (zero-padded).
• hh:mm:ss.uuuuuu: Time in hours, minutes, and fractional seconds.
• threadid: Thread ID.
• file: File name.
• line: Line number.
• msg: The logged message.