From Flow collect logs by going to Admin-> Download logs
From python, please run:
h2o.download_all_logs()
http://docs.h2o.ai/h2o/latest-stable/h2o-py/docs/h2o.html#h2o.download_all_logs
From R , please run:
h2o.downloadAllLogs()
http://docs.h2o.ai/h2o/latest-stable/h2o-r/docs/reference/h2o.downloadAllLogs.html