View Log Files Amazon EMR and Hadoop both produce log files that report status

View log files amazon emr and hadoop both produce log

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View Log Files Amazon EMR and Hadoop both produce log files that report status on the cluster. By default, these are written to the master node in the /mnt/var/log/ directory. Depending on how you configured your cluster when you launched it, these logs may also be archived to Amazon S3 and may be viewable through the graphical debugging tool. There are many types of logs written to the master node. Amazon EMR writes step, bootstrap action, and instance state logs. Apache Hadoop writes logs to report the processing of jobs, tasks, and task attempts. Hadoop also records logs of its daemons. For more information about the logs written by Hadoop, go to . Topics View Log Files on the Master Node (p. 283) View Log Files Archived to Amazon S3 (p. 285) View Log Files in the Debugging Tool (p. 286) View Log Files on the Master Node The following table lists some of the log files you'll find on the master node. Location Description /mnt/var/log/bootstrap-actions Logs written during the processing of the bootstrap actions. /mnt/var/log/hadoop-state-pusher Logs written by the Hadoop state pusher process. 283
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Amazon EMR Management Guide View Log Files Location Description /mnt/var/log/instance-controller (Amazon EMR 4.6.0 and earlier) /emr/instance-controller (Amazon EMR 4.7.0 and later) Instance controller logs. /mnt/var/log/instance-state Instance state logs. These contain information about the CPU, memory state, and garbage collector threads of the node. /mnt/var/log/service-nanny (Amazon EMR 4.6.0 and earlier) /emr/service-nanny (Amazon EMR 4.7.0 and later) Logs written by the service nanny process. /mnt/var/log/ application Logs specific to an application such as Hadoop, Spark, or Hive. /mnt/var/log/hadoop/steps/ N Step logs that contain information about the processing of the step. The value of N indicates the stepId assigned by Amazon EMR. For example, a cluster has two steps: s-1234ABCDEFGH and s-5678IJKLMNOP . The first step is located in /mnt/var/log/hadoop/steps/ s-1234ABCDEFGH/ and the second step in /mnt/ var/log/hadoop/steps/s-5678IJKLMNOP/ . The step logs written by Amazon EMR are as follows. controller — Information about the processing of the step. If your step fails while loading, you can find the stack trace in this log. syslog — Describes the execution of Hadoop jobs in the step. stderr — The standard error channel of Hadoop while it processes the step. stdout — The standard output channel of Hadoop while it processes the step. To view log files on the master node 1. Use SSH to connect to the master node as described in Connect to the Master Node Using SSH (p. 313) . 2. Navigate to the directory that contains the log file information you wish to view. The preceding table gives a list of the types of log files that are available and where you will find them. The following example shows the command for navigating to the step log with an ID, s-1234ABCDEFGH .
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  • Spring '12
  • LauraParker
  • Amazon Web Services, Amazon Elastic Compute Cloud

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