Sahara/WhyNotHeat

1. Why doesn’t Savanna use Heat to provision VMs *now*?
https://wiki.openstack.org/wiki/Savanna/HeatIntegration

2. Why we need Savanna? Can’t we use Heat to do what Savanna does?

 * Savanna provides bunch of Hadoop-specific features. It’ll be hard to provide them as Heat plugin
 * Savanna provides Hadoop-specific APIs and functionality. Heat use cases are mostly around provisioning/deployment.
 * Savanna provides integration with various Hadoop distributions through pluggable mechanism

Now, more details on each item. Hadoop specific features:
 * Tight Swift integration. Hadoop can read and write from/to Swift object storage. Savanna provides required configs for the Hadoop cluster.
 * Usage of anti-affinity to preserve data-redundancy of HDFS nodes

Hadoop-specific APIs and functionality:
 * Hadoop cluster scaling
 * Elastic Data Processing: https://wiki.openstack.org/wiki/Savanna/EDP

Integration with Hadoop distributions through pluggable mechanism:

Usually Hadoop cluster deployment is a multi-step operation. First step is to install management console (for instance Apache Ambari). Second step is to communicate with management console through REST API to provision Hadoop on the cluster. Savanna wraps all this operations under well-defined API.

3. Why can’t Savanna be used as a plugin for Heat?
It should be and it will be someday.