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EMR cluster logs

A cluster generates several types of log files, including:
  • Step logs — These logs are generated by the Amazon EMR service and contain information about the cluster and the results of each step. The log files are stored in /mnt/var/log/hadoop/steps/ directory on the master node. Each step logs its results in a separate numbered subdirectory: /mnt/var/log/hadoop/steps/1/ for the first step, /mnt/var/log/hadoop/steps/2/, for the second step, and so on.
  • Hadoop logs — These are the standard log files generated by Apache Hadoop. They contain information about Hadoop jobs, tasks, and task attempts. The log files are stored in /mnt/var/log/hadoop/ on the master node.
  • Bootstrap action logs — If your job uses bootstrap actions, the results of those actions are logged. The log files are stored in /mnt/var/log/bootstrap-actions/ on the master node. Each bootstrap action logs its results in a separate numbered subdirectory: /mnt/var/log/bootstrap-actions/1/ for the first bootstrap action, /mnt/var/log/bootstrap-actions/2/, for the second bootstrap action, and so on.
  • Instance state logs — These logs provide information about the CPU, memory state, and garbage collector threads of the node. The log files are stored in /mnt/var/log/instance-state/ on the master node.
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