Lesson 1

Managing your databases requires some fundamental decisions. An important decision is what type of backup you will perform, either physical or logical. We will introduce a discussion on physical and logical backups in this module. We will reserve further discussion on logical backups for the third course in this series when we talk about using the Export/Import utilities. Instead we will focus on physical backups of our database.
In particular, we will start to discuss operating our database in noarchivelog and archivelog mode. Our options for backup and recovery of a database in noarchivelog mode are very limited and will be addressed in this module. We will also discuss archivelog mode in more detail in subsequent modules. We will investigate backup and recovery strategies based on the use of archivelog mode in the third part of this series.
By the end of this module, you should be familiar with the following:

1. The differences between physical and logical backups
2. The differences between online and offline backups
3. The differences between archivelog and noarchivelog mode
4. Operating a database in noarchivelog mode
5. Configuring a database for archivelog mode and automatic archiving
6. Configuring a database for duplex archivelog mode

By the end of this module you will be able to backup and restore your database when using noarchivelog mode. So let’s get started so that we can backup our database.

When determining whether to use physical or logical backups in Oracle, there are several factors to consider:

1. Recovery requirements: Physical backups can be used for point-in-time recovery, while logical backups are used for selective recovery of specific data. If the requirement is to recover to a specific point in time, physical backups are the best option.
2. Backup size: Physical backups include all datafiles, including inactive and unused space, which can result in larger backups. Logical backups only include the data that is actually used, resulting in smaller backups.
3. Backup frequency: Physical backups can be performed less frequently than logical backups because they include all datafiles. Logical backups need to be done more frequently to ensure that all data is captured.
4. Backup storage: Physical backups can be stored on tape or disk, while logical backups are typically stored on disk.
5. Data consistency: Physical backups include all datafiles, ensuring that the data is consistent. Logical backups can include data from multiple points in time, which could result in data inconsistencies.
6. Security: Logical backups can be used to protect sensitive data as you can choose what to backup and what not, while Physical backups can backup everything in the system.
7. Data archiving: Logical backups are useful in archiving specific data that is no longer in use but still needs to be retained for compliance or reporting purposes.

Ultimately, the choice between physical and logical backups will depend on the specific requirements of the organization and the type of data being backed up. In many cases, a combination of both physical and logical backups is used to provide a comprehensive backup and recovery strategy.