Hi,
Sometimes You can get “ORA-12549: TNS:operating system resource quota exceeded ” error.
Details of error are as follows.
ORA-12549: TNS:operating system resource quota exceeded
Cause: The current user has exceeded the allotted resource assigned in the operating system.
Action: Acquire more operating system resource, or perform a different function.
This error is related with the OS box is running out of maxuproc (Maximum number of PROCESSES allowed per user).
To solve this error, increase the maxuproc kernel parameter (e.g. between 25% & 50% more)
maxuproc= (<Current value> X 1.50)
Or Check your RAM size and free memory, if there is no free memory, increase RAM Size.
Do you want to learn more details about RMAN, then read the following articles.
https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/