I have few question as below .
Oracle have any best practices for OS patching?
Is OS patching supported in a rolling fashion?
For Example : i have 4 nodes RAC database running on windows servers.if nodes 1& 2 has been patched while 3&4 Nodes has old patching levels of drivers or patches until the patching is completed .
1)Will the instances in the cluster be ok to run with different levels/version of patching ?
2)What if something fails, how long could we run with different versions/levels of patching?
3)would it be best to do a complete shutdown of the cluster and patch all nodes at the same time, once OS patches applied, then bring back the cluster?