Zookeeper.out file contains log for zookeeper server. you can refer to below thread to enable log rotating for zookeeper. This way you can avoid too big log files. https://community.hortonworks.com/questions/39282/zookeeper-log-file-not-rotated.html ... View more

JMX metrics can provide you compaction related parameters. http://<region server>:16030/jmx ... View more

---->How region server will use heap and what are the parameters will occupy heap memory Region server heap memory consumption is mainly dependent on below three. - Block cache (Buffer maintained in heap for read) - Memstore Size (Buffer maintained in heap for write and flush) - Other Objects created within region server while during various operations. Below two are the parameter which controls the max % of heap block cache and block cache consume. hfile.block.cache.size hbase.regionserver.global.memstore.size =>Below links will help in understading region server configuration for block cache/memstore and region server sizing. https://hbase.apache.org/book.html#perf.rs.memstore.size https://hbase.apache.org/book.html#ops.capacity.regions.count https://hbase.apache.org/book.html#block.cache.usage -----> Is region server will use only 16 GB heap or even other space of RAM Region server will comsume maximum = 16GB of heap + XX:MaxDirectMemorySize which you have configured. MaxDirectMemorySize—The JVM has a kind of memory called direct memory, which is distinct from normal JVM heap memory, that can run out. You can increase the direct buffer memory either by increasing the maximum heap size (see previous JVM Heap Size), which increases both the maximum heap and the maximum direct memory, or by only increasing the maximum direct memory using -XX:MaxDirectMemorySize. The following parameter added to the Java application startup increases the maximum direct memory size to 256 megabytes: ... View more