Question-91: What do you mean by Java heap size?

Answer: Java is one operating system process while running it requires memory and it gets the memory while starting the Java process and that memory is known as is Java heap memory there are other memory as well as in Java process like stack memory.  

Question-92: Cassandra node is a java process, so it is logical to provide maximum memory as Java heap memory which is available on that node?

Answer: yes, Cassandra is a java process and defining more heap memory is helpful. However, keep in mind that Casandra uses other native caching as well like chunk cash. Hence you should provide one half or one fourth available memory as heap memory.  

Question-93: What is transparent hugepages features?

Answer: In the recent version of the Linux transparent Hugepages feature is enabled by default. With this feature kernel tries to allocate memory in large chunks which is usually 2MB and not 4K. To improve performance by reducing the number of pages the CPU must track, if application tries to allocate memory based on the 4K pages and this can cause performance problems because Linux tries to defragment 2 MB pages. To avoid this issue, we should disable the defrag for the transparent hugepages.

Question-94: “dse.yaml” file is a replacement for Cassandra.yaml file when you use Datastax enterprise solution?

Answer: No, you still have to use Cassandra.yaml file for basic configuration. The dse.yaml file is the primary configuration file for security, search, graph and analytics product solution provided by datastax.

Question-95: If you make some changes in the Cassandra.yaml file, then is it required to restart the node?

Answer: Yes, it is required that whenever you change any property in the Cassandra.yaml file. Then this to be effective you need to restart the Cassandra node on which changes were made.