Saw errors when creating a 19c RAC database by DBCA like the following.
[oracle@primary01 ~]$ vi $ORACLE_BASE/cfgtoollogs/dbca/ORCLCDB/trace.log_2020-10-13_19-42-05PM
...
ORA-19504: failed to create file "+DATA01/ORCLCDB/pdbseed/sysaux01.dbf"
ORA-17502: ksfdcre:4 Failed to create file +DATA01/ORCLCDB/pdbseed/sysaux01.dbf
ORA-15173: entry 'pdbseed' does not exist in directory 'ORCLCDB'
Of course, the whole database creation failed.
Rationale
This is because we choose NOT to use Oracle-Managed File (OMF) for the RAC database, RMAN cannot find the existing directory to restore data files. (Is it a bug?)
Solutions
You can either choose to use OMF during database creation, or using asmcmd mkdir to create necessary directories by grid in advance. For example:
[grid@primary01 ~]$ asmcmd mkdir +DATA/ORCLCDB
[grid@primary01 ~]$ asmcmd mkdir +DATA/ORCLCDB/pdbseed
[grid@primary01 ~]$ asmcmd mkdir +DATA/ORCLCDB/ORCLPDB
The format of directory is:
+<disk_group_name>/<cdb_name>/<pdb_name>
As you can see, we created a folder named PDBSEED for PDB$SEED, the template of pluggable databases.
There's a successful example of creating a 19c RAC database by DBCA without using OMF.