Recovering Databases with RMAN - OCP: Oracle Database 12c Administrator Certified Professional - page 230

where the online redo log file has accidently been deleted and the ARCH n process is not
able to process that missing online redo log file.
If you have to use the ALTER DATABASE CLEAR LOGFILE command (especially if you use
the UNARCHIVED option), you should always immediately perform a full backup of your
database because any previous backups are going to be unusable past the point that you
issued the ALTER DATABASE CLEAR LOGFILE command. Here is an example of using the
ALTER DATABASE CLEAR LOGFILE command:
Alter database clear unarchived logfile '/u01/oradata/orcl/redolog01a.log';
Summary
As you can see, there are several ways to recover a database with RMAN. From database
recoveries to tablespace recoveries to data file recoveries and beyond, there is a lot that can
go wrong—and a number of different ways to fix what may go wrong.
For your OCP exam, you will want to be familiar with the different kinds of database
restores and recoveries that are possible. In this chapter we have provided you with the
information you need to successfully answer the RMAN-recovery-oriented questions.
We strongly recommend that you practice these recovery techniques before you take
the test. This is particularly important if you have not had any experience with RMAN
restore and recovery operations. You might use the exercises in this chapter to give you
more experience with recovery of your database and to better prepare you for the exam.
Backup and recovery are the lifeblood of being a DBA. Truly there is nothing more
important than knowing not only how to recover your database but also how to craft an
overall backup and recovery strategy for your database.
Exam Essentials
Describe the basic process used when performing an RMAN database restore and recovery.
Understand the essentials behind RMAN backup and recovery. Know what might be required
to prepare for an RMAN recovery. Understand the basic steps of a typical RMAN recovery
and what they are for.
Know how to use the RESTORE command. Understand the use of the RESTORE com-
mand. Know the different options of the RESTORE command, such as RESTORE DATABASE ,
RESTORE TABLESPACE , and RESTORE DATAFILE . Understand what happens when you call
the RESTORE command.
Know how to use the RECOVER command. Understand and be able to successfully use the
RECOVER command. Know the different options of the RECOVER command, such as RECOVER