Question-51: In CDP Private Cloud Base cluster, which of the following correct statements with respect to RAM allocation.

Question-51: In CDP Private Cloud Base cluster, which of the following correct statements with respect to RAM allocation.

1. Applications such as Impala and Cloudera Search are often configured to use large amounts of heap.
2. It is critical to performance that the total memory allocated to all Hadoop-related processes (including processes such as HBase) is less than the total memory on the node.
3. Oversubscribing the memory on a system can led to the Linux kernel’s out-of-memory process killer being invoked and important processes being terminated.
4. Performance might be affected by over-allocation of memory to a Hadoop process, as this can lead to long Java garbage collection pauses.

Answer: 

Exp: 

Allocate at least 4 GB memory for the operating system and other non-Hadoop use (although this amount may need to be higher if additional non-Hadoop applications are running on the cluster nodes, such as third-party active monitoring/alerting tools). The more services you are running, the more memory will be required; you will need to use more capable hosts to accommodate these needs.

It is critical to performance that the total memory allocated to all Hadoop-related processes (including processes such as HBase) is less than the total memory on the node, taking into account the operating system and non-Hadoop processes. Oversubscribing the memory on a system can lead to the Linux kernel’s out-of-memory process killer being invoked and important processes being terminated. Performance might be affected by over-allocation of memory to a Hadoop process, as this can lead to long Java garbage collection pauses.  For processes such as HBase, factor in aspects such as off heap bucket cache configuration.

For optimum performance, confer with your hardware vendor for defining optimal memory configuration layout. Whilst 128 GB RAM can be accommodated, this typically constrains the amount of memory allocated to services such as YARN and Impala, thereby reducing the query capacity of the cluster. 256 GB RAM is recommended with higher values also possible.