Task Nodes

A task node contributes only compute resources for TaskTrackers and does not contribute any disk space to the cluster's storage pools. Generally, when permanently adding a node to a cluster, you want the node to contribute both compute and storage resources. However, there are cases for which it is preferable to prevent the cluster from storing data on a particular node. For example, Task Nodes are useful if you need the ability to add compute resources to the cluster at will, and later remove them spontaneously without provisioning for data on the nodes to safely replicate elsewhere.