Failure Group selection rules

Failure groups are created based on rack allocation of the nodes. One rack mapping file is supported (Rack Mapping File).

Ambari reads this rack mapping file, and assigns one failure group per rack. The rack number must be three or greater than three. If rack mapping file is not provided, virtual racks are created for data fault toleration.

1. If the node number is less than five, each node is on a different rack.
2. If the node number is greater than or equal to five, and node number is less than 10, every two nodes are put in one virtual rack.
3. If the node number is greater than or equal to ten and node number is less than 21, every three nodes are put in one virtual rack.
4. If the node number is greater than or equal to 21, every 10 nodes are put in one virtual rack.