One of the main roles of the master is to decide which shards to allocate to which nodes, and when to move shards between nodes in order to rebalance the cluster.

There are a number of settings available to control the shard allocation process:

Besides these, there are a few other miscellaneous cluster-level settings.

All of the settings in this section are dynamic settings which can be updated on a live cluster with the cluster-update-settings API.