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Control File: RMAN can conduct all necessary backup and recovery operations using just the Control File to store the RMAN repository information. This ability increases the importance of protecting the Control File as part of your backup strategy. |
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Enable Oracle’s Control File Autobackup feature. This feature causes RMAN to back up the Control File automatically, and also lets RMAN restore the Control File Autobackup without access to a repository. |
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Keep a record of your Oracle Database ID (DBID), which may be required to recover the database when the Control File is lost. |
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Use a minimum of two multiplexed or mirrored Control Files on separate disks. |
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Recovery Catalog: You can also use an external Oracle database to store the RMAN repository. This external database is known as the Recovery Catalog. While the Control File has finite space for records of backup activities, a Recovery Catalog can store a longer history. The complexity of administering a Recovery Catalog database can be offset by the convenience of having the extended backup history available for a recovery that precedes the history in the Control File. |
Plug‑in for Oracle supports following types of RMAN backups:
The Incremental Backups are further classified as follows:
An RMAN Full Backup is a backup of a datafile that includes every allocated block in the file being backed up. A Full Backup of a datafile can be an image copy, in which case every data block is backed up. You can also store it in a backup set, in which case datafile blocks not in use may be skipped. An RMAN Full Backup cannot be part of an Incremental Backup strategy, that is, it cannot be the parent or base of a subsequent Incremental Backup.
RMAN’s Incremental Backups are multilevel. Each incremental level is denoted by a value of 0 or 1.
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Level 0 Incremental Backup: A Level 0 Incremental Backup, which is the base for subsequent Incremental Backups, copies all blocks containing data, backing up the datafile into a backup set just as a Full Backup would. |
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Level 1 Incremental Backup: A Level 1 Incremental Backup can be either of the following types: |
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Cumulative Incremental Backup: In a Cumulative Incremental Backup, RMAN backs up all the blocks used since the most recent Level 0 Incremental Backup. Cumulative Incremental Backups speed up restores by reducing the number of Incremental Backups you need to include in the recovery process. Cumulative Backups require more space and time than Differential Backups because they duplicate the work done by previous backups at the same level. |
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Differential Incremental Backup: In a Differential Incremental Backup, RMAN backs up all blocks that have changed since the most recent Cumulative or Differential Incremental Backup, whether at Level 1 or Level 0. |
Protecting the Control File is critical in many recovery situations. Plug‑in for Oracle provides two methods for protecting the Control File: Manual Backups and Autobackups. However, when using the RMAN method, you can perform either Control File Autobackups or Manual Backups but not both. When the Control File Autobackups are enabled for a database, Manual Control File Backups are not available.
The User Managed and RMAN backup methods both support Manual Backup of the Control File.
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Manual Backup of Control File with User Managed backup method: With the User Managed backup method, the plug-in does not use the active Control File for backup and restore. During backup, the plug-in saves a snapshot of the Control File to the user-specified Control File Save Filename (Full Path), and then backs up this copy of the Control File. This process ensures that a consistent copy of the Control File is protected. During restoration, the plug-in restores the Control File to the Control File Save Filename (Full Path) to ensure that the active Control File is not inadvertently overwritten. Manually copy this file to the original location as required. To ensure that a recent copy of the Control File is always available, include it with each User Managed backup. |
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Manual Backup of Control File with RMAN backup method: When Control File Autobackups are disabled and the Control File node is explicitly selected on the NetVault Backup Selections page, the plug-in uses RMAN’s BACKUP CURRENT CONTROLFILE to back up the Control Files. To ensure that a recent copy of the Control File is always available, include it with each RMAN backup. |
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