This section provides information on the use cases and fail over scenarios for high availability of the HDP Master Services (NameNode and JobTracker).
Use Cases
This solution enables the following Hadoop system administration use cases:
- Planned downtime of the HDP Master Service (for maintenance tasks like software or hardware upgrade) 
- Unplanned failure of the HDP Master Service 
Fail over scenarios
The solution deals with the following faults:
- HDP Master service failure 
- HDP Master JVM failure 
- Hung HDP Master daemon or hung operating system 
- HDP Master operating system failure 
- Virtual machine failure 
- ESXi host failure 
- Failure of the NIC cards on ESXi hosts. 
- Network failure between ESXi hosts. ![[Note]](../common/images/admon/note.png) - Note - Some double faults are not handled (such as failure of multiple ESXi hosts). 


