HBase architecture (RegionServer, HMaster) in Hadoop - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the role of the HMaster in HBase architecture?

The HMaster manages the cluster, handles metadata operations, assigns regions to RegionServers, and monitors their health. It acts like a manager coordinating the work of RegionServers.

beginner

What is a RegionServer in HBase?

A RegionServer hosts and manages regions, which are subsets of tables. It handles read and write requests for the data in those regions, similar to a worker serving data to users.

intermediate

How does HBase split data across RegionServers?

HBase splits tables into regions based on row keys. Each RegionServer manages one or more regions, distributing data and load evenly across the cluster.

intermediate

What happens if a RegionServer fails in HBase?

The HMaster detects the failure and reassigns the regions managed by the failed RegionServer to other active RegionServers to keep the system running smoothly.

advanced

Why is HMaster considered a single point of control but not a single point of failure?

HMaster controls the cluster but does not serve data directly. If it fails, a backup HMaster or a standby HMaster takes over, so data serving continues without interruption.

What component in HBase assigns regions to RegionServers?

A ZooKeeper

B HMaster

C RegionServer

D HDFS

The HMaster is responsible for assigning regions to RegionServers.

Which component handles read and write requests in HBase?

A HMaster

B DataNode

C NameNode

D RegionServer

RegionServers handle the actual read and write requests for data.

If a RegionServer fails, what does HBase do?

A Reassigns regions to other RegionServers

B Stops all operations

C Deletes the data

D Restarts the HMaster

The HMaster reassigns the regions from the failed RegionServer to other active RegionServers.

What is a region in HBase?

A A client application

B A backup server

C A subset of a table managed by a RegionServer

D A metadata file

A region is a part of a table that a RegionServer manages.

Which system helps HBase maintain high availability of the HMaster?

A Backup HMaster

B Multiple RegionServers

C HDFS replication

D ZooKeeper

A backup HMaster can take over if the active HMaster fails, ensuring high availability.

Explain the roles of HMaster and RegionServer in HBase architecture.

Think of HMaster as the manager and RegionServers as workers.

Describe what happens when a RegionServer fails in an HBase cluster.

Focus on fault tolerance and recovery.