Introduction to Oracle database backup and recovery features

Oracle database backup and recovery is not accessible to every Oracle database administrator. Oracle Database Backup has three methods, each of which has different recovery features. Therefore, you should integrate database and file system backup, logical backup, and physical backup.

I. Oracle database backup policy

1. At the operating system level, a large disk array is used to automatically distribute each database file on each physical disk through the disk image technology. In this way, when a disk is physically damaged, the operating system will automatically trigger the image disk to replace the invalid disk to ensure the normal operation of the database.

Because we use dual-server, we keep a backup database on the other server. The backup database has the same parameter status as the database in use. In this way, you only need to perform the least necessary restoration in case of database faults, minimizing the recovery time.

Maintain backup of multiple control files on multiple physical disks. The control file is used to guide Oracle during database recovery. Therefore, the backup of multiple control files ensures that available control files can be used for database recovery in the event of a disk failure.

Enables the database to run in ARCHIVELOG mode, and stores archived logs on the Logical Disk of another image.

An online backup operation is performed every night to back up all data files, all archived log files, and one control file.

An Export operation is performed once a week.

Ii. Oracle database recovery policy

1. instance failed

When an instance fails, Oracle database recovery is automatically performed. Instance failure is generally caused by Server failure. When the database instance fails, restart the server, start the database, and check data files and online log files in Oracle, and synchronize all files to the same time point.

2. disk failure

If a control file is lost, you only need to close the database and copy it from the place where the control file is retained.

If the data file is lost, you can use the online backup of the previous night to restore it. The steps are as follows:

(1) store the lost file in the original location from the backup.

(2) load the database

(3) restore the database

(4) Open the database

3. delete or modify objects by mistake

In this case, we generally want to trace the time point before the error occurs. This is called time point recovery. Follow these steps:

(1) from the current database output (Export), input (Import) to the backup database, so that the backup database is consistent with the current database.

(2) scroll forward to the time point before the error occurs.

(3) output the logical objects affected by errors from the standby database.

(4) use the output file generated in the previous step to input the affected objects to the current database.

Iii. Oracle user role management

1. assign different user roles to all clients based on their work nature.

2. Grant different database object access permissions to different user roles based on their data sources.

Based on the preceding security policies, you can prevent unauthorized users from accessing the database and restrict authorized users from manipulating the database. This prevents the database from losing any data after a fault occurs, in addition, the database can be quickly restored to the time point before the fault occurs, ensuring data security and continuous operation of the entire system to the maximum extent.

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