hdfs rack awareness

[nvtkaszpir]

HDFS uses rack awareness to contol where to store replicas https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-common/RackAwareness.html

Notice this is not the same as antiaffinity, and antiaffinity can only solve this issue partially

Current setup does not support rack awareness, not to mention that it is quite complex and actually require additonal info about nodes used to host pods for hdfs datanodes, such as labels on the nodes.

Need to investigate this in the future, just adding this as issue to keep it in mind.