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This has been observed for Ambari 1.7. I know Ambari 1.7 is very old now however if some people are still using it and facing same issue then this post can save your lot of time! 🙂
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We know that Ambari 1.7 has Ganglia for reporting metrics.
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Our issue was, we were unable to get service metrics for YARN service, below was the exact scenario:
1. In Ganglia UI, I was able to get graphs for the YARN Metrics.
2. In Ambari UI, I was able to see metrics for other services like HDFS etc.
3. This issue was observed on one of our customer's cluster.
4. I did setup same cluster on my local system however I was not able to reproduce this issue.
5. Only difference in customer's and my cluster was, customer was having RM HA and I had installed single node instance.
6. There was no error while getting metrics, please see below screenshot when metrics were not visible.
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How to troubleshoot:
1. Click on any of the metrics, say 'Nodemanagers' --> This will open graph in big window.
2. Open the developer tools from Chrome/Firefox and inspect the network activities.
3. Notice the REST call from where its trying to fetch metrics.
4. Now do the RM failover and try to follow step 1-3 again.
5. Same REST call? No difference.
6. If you flip the RMs, Graphs will start populating the Data.
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Root Cause:
If you look at hadoop-metrics2.properties file, it has only one RM host(initial rm1) hardcoded for resourcemanager.sink.ganglia.servers
resourcemanager.sink.ganglia.servers=rm1.crazyadmins.com:8664
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Workaround:
Make same RM host as active RM which you get in REST API as a output of troubleshooting step 4.
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Permanent fix:
Edit /etc/hadoop/conf/hadoop-metrics2.properties file and add another RM host:
E.g.
resourcemanager.sink.ganglia.servers=rm1.crazyadmins.com:8664,rm2.crazyadmins.com:8664
Note - This file is not managed by Ambari 1.7. Feel free to modify on both the RM hosts and restart RMs via Ambari after the modifications.
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Hope you enjoyed this article! Please comment if you have any questions. Happy Hadooping!! 🙂
