Cloudera Docs

Ozone Placement Policy

Ozone uses Placement Policies to decide how to distribute Ratis and Erasure Coded containers among DataNodes. This document provides an overview of the available policies and describes how to configure them.

Uses of Placement Policy:

  1. Ozone creates pipelines of DataNodes for Ratis or Erasure Coded "Open" containers. Ozone selects DataNodes based on load balancing and network topology.
  2. Ozone selects the DataNodes that must get the replicas of a "Closed" Ratis or Erasure Coded container. This logic is used when resolving under replication or over replication of a container, for example. This is different from the above point because Closed containers are not part of write pipelines. You can configure this using ozone.scm.container.placement.impl for Ratis containers.

This document discusses the placement policies available for configuring ozone.scm.container.placement.impl.