When you create a service to compute, for example in HD-Insight you can create a cluster which remains active once it’s created or, in the other hand, stop (will be ‘deleted’) after some amount of innactivities.

If you, like me, your first approach was with the Azure Service you’ll notice that the name if the cluster is deleted after some time of inactivity is an Ephemeral cluster.

In other words:

An ephemeral cluster is a cloud platform cluster that you create to run mappings and
other tasks, and then terminate when tasks are complete

informatica

The key befits of this type of cluster is that you may save cloud resources. But one trade-off is that you need to wait until the clusters are provisioned because, at the end of the day, somebody has to create the environment for the jobs to run.

Sources:

• Microsoft Spect: HD-Insight
• Informatica Presentation