Hi, @kras Thank you for writing back with your observation. Can you please check the below details as well? 1) When the Region Server JVM reports High CPU, Open "top" Command for the Region Server PID, 2) Use "Shift H" to open the Thread View of the PID. This would show the Threads within the Region Server JVM with CPU Usage, 3) Monitor the Thread View & Identify the Thread hitting the Max CPU Usage, 4) Take Thread Dump | JStack of Region Server PID & Compare the Thread with the "top" Thread View consuming the Highest CPU. 5) Check the CUP usage of the other services that are hosted on the Region Server host. The above Process would allow you to identify the Thread contributing towards the CPU Usage. Compare the same with other Region Server & your Team can make a Conclusive Call to identify the reasoning for CPU Utilization. Howsoever Logs are reviewed, Narrowing the Focus of JVM review would assist in identifying the Cause. Review shared Link for additional reference. Ref: https://www.infoworld.com/article/3336222/java-challengers-6-thread-behavior-in-the-jvm.html https://blogs.manageengine.com/application-performance-2/appmanager/2011/02/09/identify-java-code-co... https://blog.jamesdbloom.com/JVMInternals.html Thanks & Regards, Prathap Kumar.
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Hello @kras Unfortunately, there is no Clean Way to remove such Secondary Regions. The concerned issue is tracked via HBASE-24720. 1 Quick Fix would be to create a Snapshot on say, Table_A (Which had RegionReplication reduced from 2 to 1), CloneSnapshot to a new Table (Table_B). Table_B would have 1 Region. - Smarak
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