When you checkpoint a Fluent job, LSF creates a checkpoint trigger file (check) in the job subdirectory, which causes Fluent to checkpoint and continue running. A special option is used to create a different trigger file (exit), to cause Fluent to checkpoint and exit the job. Fluent uses the LSB_CHKPNT_DIR environment variable to determine the location of checkpoint trigger files. It checks the job subdirectory periodically while running the job. Fluent does not perform any checkpointing unless it finds the LSF trigger file in the job subdirectory. Fluent removes the trigger file after checkpointing the job.