Following are the components of the Region Server of HBase :
BlockCache : It resides on Region Server and stores data in the memory that is read frequently.
WAL : WAL or Write Ahead Log is a file that is attached to each Region Server located in the distributed environment.
MemStore : MemStore is the write cache that stores the input data before it is stored in the disk or permanent memory.
HFile : HDFS stores the HFile that stores the cells on the disk.
