Compaction in HBase
There is a complete process in which to decrease the storage and also to decrease the number of disks seeks needed for a read, HBase combines HFiles, so that process is known as compaction. Although, it is of two types:
Minor Compaction
while HBase takes smaller HFiles and recommits them to bigger HFiles, that is Minor Compaction.
Major Compaction
But while it merges as well as recommits the smaller HFiles of a region to a new HFile is Major compaction.
learn more about compaction in HBase, follow the link: HBase Architecture – Regions, Hmaster, Zookeeper