Containers

Containers are big binary units (5Gb by default) which can contain multiple blocks:

Blocks are local information and not managed by SCM. Therefore even if billions of small files are created in the system (which means billions of blocks are created), only of the status of the containers will be reported by the Datanodes and containers will be replicated.

When a container is created it starts in an OPEN state. When it’s full (~5GB data is written), container will be closed and becomes a CLOSED container.