Creating Image Copies of database in Oracle 12c

An Oracle DBA can create a backup of a database using an image copy in Oracle 12c. Image copies offer several advantages and can be created using RMAN or other methods.
Understanding Image Copies:

• Direct Copies: Image copies are identical, byte-for-byte copies of database files (datafiles, control files, archived redo logs).
• Created Outside RMAN: They can be generated using operating system commands or third-party tools, but RMAN offers integration and management benefits.
• Not Proprietary: Image copies are not in Oracle's proprietary format, making them accessible by other tools and potentially usable for cross-platform migration.

Creating Image Copies with RMAN:

1. Connect to RMAN:
   

   rman target /
   

2. Allocate Channels (optional):
   

   allocate channel ch1 device type disk;
   

3. Create Image Copies:
   

   backup as copy database;  -- Backs up all datafiles
   backup as copy tablespace users;  -- Backs up specific tablespace
   backup as copy datafile 4;  -- Backs up a specific datafile
   

Key Considerations:

• RMAN Integration: RMAN can track and manage image copies, enabling their use for restore and recovery operations.
• Validation: RMAN validates image copies during creation, ensuring data integrity.
• Incremental Updates: Image copies can be incrementally updated using RMAN's incremental backup features.
• Switching to Activate: During recovery, you can directly "switch" to image copies, potentially reducing downtime.

Other Methods for Creating Image Copies:

• Operating System Commands: `cp`, `copy`, or `dd` utilities.
• Third-Party Tools: Storage vendors' tools for efficient image copy creation.

Image Copies Offer Flexibility and Efficiency:

• Faster Restores: Direct file copies can often be restored faster than RMAN backup sets.
• Flexible Management: Can be used with or without RMAN for backup and recovery.
• Cross-Platform Potential: Accessibility outside RMAN can facilitate platform migrations.

Earlier, you learned the basics of how to create a backup set, a topic that will be explored further in the next module.
The other type of backup you can perform is an image copy.

An image copy is essentially a copy of an operating system file. You can create an image copy of a data file, an archived redo log, and the control files for a database. If you need to restore a database from an image copy, you do not need to restore the database explicitly. Instead, Oracle performs an implicit switch command, which points the database instance at the new data file.

You can use the copy command to make an image copy with RMAN. The syntax for this command is:

copy filetype TO filespec

Three Sets of Values: There are three sets of values you can use for filetype--

1. datafile
2. archivelog, and
3. current controlfile
.

A path delimited within single quotes follows the first two types. The current controlfile type will simply make an image copy of the most current control file. The filespec is the pathname to the destination file for the image copy. You can also make copies of existing image copies with the file types of datafilecopy and controlfilecopy.

The "Backup Manager" is no longer a standalone component within Oracle Enterprise Manager (OEM) as of release 12c. Oracle has shifted its backup and recovery focus to:

1. Recovery Manager (RMAN):
   • Serves as the primary tool for comprehensive database backup and recovery tasks.
   • Integrated within OEM for management and monitoring.
   • Offers automation, advanced features, and integration with media management software.
2. Cloud Control Backup and Recovery Features:
   • OEM Cloud Control provides several backup and recovery functionalities:
     
     1. Backup and Recovery Wizard: Simplifies common backup and restore operations.
     2. Backup Scheduling: Automates recurring backups.
     3. Backup Monitoring and Reporting: Tracks backup status, success rates, and alerts.
     4. Integration with RMAN: Allows management of RMAN backups from the OEM console.

Changes in OEM 12c and Later:

• Backup Manager Removed: The dedicated "Backup Manager" component was discontinued.
• Focus on RMAN: Oracle emphasizes RMAN as the preferred backup and recovery solution.
• Enhanced Cloud Control Features: OEM provides a unified interface for managing various database tasks, including backup and recovery through RMAN integration.

Key Advantages of RMAN:

1. Comprehensive Features: Handles full, incremental, and differential backups, block-level corruption detection, restore and recovery operations, reporting, and more.
2. Automation: Automates backup and recovery tasks, reducing manual effort and errors.
3. Integration with Media Management Software: Connects with third-party tools for efficient storage management.
4. Centralized Management: Can be managed through OEM Cloud Control, providing a single interface for various database administration tasks.

In the next lesson, you will learn how to create image copies in parallel for improved performance.