Upgrading the cluster’s underlying OS
Operating system requirements
For many, this is a process that takes time and orchestration between multiple teams within your organization. Two high-level guidelines for moving from one major operating system version to another is as follows:
In-Place and Restore:
Perform an In-place OS refresh and use Ambari Restore Host feature
Move and Decom:
Move Masters and Decom/Recom Workers
Each option has advantages and disadvantages and high-level decision criteria.