Saturday, May 5, 2018

Hbase - Architecture

Hbase architecture works in similar fashion like the Master Slave architecture.The complete architecture is divided into the three parts :-  HMaster , HRegions and Zookeeper.

HRegion Server :-  The table and the data is  stored in the Regions and  are  handled by the HRegion Servers.A Hbase can have multiple Region servers and each region server can have  multiple regions.The data is stored in the regions and when the region is full the data is flowed to the other regions.The data is partitioned across the regions on the basis of the row key.The Region Servers are present on the Hadoop data node and it is not necessary that there are as many Hbase region server as there are HDFS nodes.

Actions Performed By HRegion Server :-

  1. Responsible for hosting and managing Regions.
  2. Splits the Regions automatically when the table grows.
  3. Manages the read and write operation.
  4. Communicates with the client directly.



HMaster Server :- Normally in a Hadoop ecosystem , the HMaster runs on the same node on which the Name Node runs.It is used for managing and monitoring  the Region Server.

Actions Performed By HMaster Server :- 

  1. Assigns the HRegion Server on startup and reassign the HRegion server during recovery and load   balancing.
  2.  It coordinates and manages the HRegion Servers. 
  3. Responsible for DDL operations like Creating Table ,column families and deleting tables.

Zookeeper :- Zookeeper is a distributed coordination service to maintain the server state in the cluster.

Actions Performed By Zookeeper :-

  1. Zookeeper acts like a coordinator inside the server cluster by communicating through the sessions.
  2. Every Region server and HMaster sends the heartbeat to the Zookeeper , notifying that the server is in active state.Once the heartbeat will get stopped then the zookeeper assumes that the server is no long available and starts the recovery process.
  3. Zookeeper manages the .META severs path which helps in client searching for any particular region within the region servers.

We will go through Read and Write in HBase in our next tutorial.



Further Reading :- https://hbase.apache.org/

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