Enabling Dynamic Log Levels
Storm allows users and administrators to dynamically change the log level settings of a running topology. You can change log level settings from either the Storm UI or the command line. No Storm processes need to be restarted for the settings to take effect. The resulting log files are searchable from the Storm UI and logviewer service.
Standard log4j levels include DEBUG, INFO, WARN, ERROR, and FATAL, specifying logging of coarse or finer-grained levels of informational messages and error events. Inheritance is consistent with log4j behavior. For example, if you set the log level of a parent logger, the child loggers start using that level (unless the children have a more restrictive level defined for them).