Sorted:

What is the role of a RegionServer in HBase?

What is the BlockCache in HBase?

How is data deletion implemented in Cassandra?

How should Cassandra be upgraded and scaled?

Does Cassandra support deployment across multiple data centers?

How is Cassandra’s delayed query optimization achieved?

How is data repair carried out by Cassandra?

What are the best practices for deploying Cassandra at scale?

How does data compression work in Cassandra?

Atlas address issues related to data quality and consistency?