- Oracle Database 12c Backup and Recovery Survival Guide
- Francisco Munoz Alvarez Aman Sharma
- 390字
- 2021-04-02 10:19:56
Types of backup
Now that you understand all types of possible failures that could affect your database, let's take a closer look at the definition of backup and the types of backups that are available to ensure the recoverability of our data.
A backup is a real and consistent copy of data from a database that could be used to reconstruct the data after an incident. Consequently, there are two different types of backups available, which are:
- Physical backups
- Logical backups
A physical backup
A physical backup is a copy of all the physical database files that are required to perform the recovery of a database. These include datafiles, control files, parameter files, and archived redo log files. As an Oracle DBA, we have different options to make a physical backup of our database. Backups can be taken using user-managed backup techniques or using Recovery Manager (RMAN). Both techniques will be discussed in more detail later in this book. Physical backups are the foundation of any serious backup and recovery strategy.
A logical backup
Oracle uses Oracle Data Pump to allow us to generate a logical backup that can be used to migrate data or even do a partial or full recovery of our database. The utilities available are the Data Pump Export program (expdp) and the Data Pump Import program (impdp).
Many people have a misconception of these tools in thinking that they can only be used to move data. Data Pump is a very flexible and powerful tool that if well utilized can easily become a DBA's best friend. It is not just for moving data. It can also play a crucial role in your backup and recovery strategy.
Chapter 9, Understanding Data Pump and Chapter 10, Advanced Data Pump will go into more detail about the use of Data Pump for logical backup and recovery.
Note
The old Import and Export utilities
In the previous versions of Oracle we used to work with similar utilities called exp and imp. The exp utility is deprecated since Oracle 11g, but the imp utility is still currently supported by Oracle. The imp utility allows us to recover any backup generated by the old exp program. Just keep in mind that the use of exp is not supported anymore by Oracle and using it can bring future trouble to your environment.