Which of the following files cannot be backed up by RMAN? (Choose all that apply.)
A. Database datafiles
B. Control files
C. Online redo logs
D. Database pfiles
E. Archived redo logs
RMAN will not back up online redo logs or database parameter files.RMAN will back
up database server parameter files(spfiles)however.
C 是归档后，使用 rman备份。而 pfile 是客户端的文件，也不能使用 rman 备份。
ARCHIVELOG mode时，rman backup中会发出alter system switch logfile 的命令，并备份archivelog ,等同于备份了online redo 而noARCHIVELOG mode时，不能online backup,所以，redo log是没有用的.
另外，如果你备份online redo log，并在恢复时使用，覆盖现有的online redo log，可能会引起数据丢失
The RMAN command for making backups is BACKUP. The RMAN BACKUP command supports backing up the following types of files:
Datafiles and control files
Server parameter file
Archived redo logs
RMAN backups
Although the database depends on other types of files, such as network configuration files,password files, and the contents of the Oracle home, you cannot back up these files with RMAN.
Likewise, some features of Oracle Database, such as external tables, may depend upon files other than the datafiles, control files, and redo log. RMAN cannot back up these files. Use some non-RMAN backup solution for any files not in the preceding list.
When you execute the BACKUP command in RMAN, the output is always either one or more backup sets or one or more image copies. A backup set is an RMAN-specific proprietary format,whereas an image copy is a bit-for-bit copy of a file. By default, RMAN creates backup sets.