Recovery

Selecting the Type of Recovery

5.1.3Automatic Recovery (Crash Recovery)

In the case of a fully-automatic recovery, NSR-ORA deals with the entire task of restoring the damaged tablespaces and redolog files without any further operator intervention. It communicates with ORACLE, enquires which tablespaces are damaged and recreates them. Then it asks for the necessary redolog files and recreates these, if they have already been backed up. It then tells ORACLE to perform a roll forward using the redolog files.

Within a recovey process three phases are to be distinguished:

Analyzing the Database (Crash Analysis)

During the database is examined an analysis with regard to a loss of data- base files is performed. Therefore, first of all, NSR-ORA tries to close the database. If this action fails the database is shut down hard using the shutdown abort command. Then several informations required for a following restore and the recovery of the database are generated by analyzing data- base views.

If this examination shows that no database files were lost the database will be reset to normal operation mode again already within this phase.

Restoring the database files

The restore of the database files will be done using the information genera- ted in the analyzation phase. This phase is unnecessary, if the previous exa- mination has not found any database files corrupted.

Recovering the database

The recovery on the database level is performed offline, i.e. the database is not usable. During this phase all database files are switched to offline mode to assure, that all the database files are recovered. In addition the archiving monitor is stopped to prevent it from obstructing the recovery process.

Thereby the tablespaces are recovered parallel whereby the parameters

NSR_MAX_RECOVER and NSR_MAX_DEVICES rule the parallelism and/or the number of backup devices to be used.

Subsequently all offline redolog files (after restoring) will be redrawn. After a final check for the recovery activities having been completed successfully the database is reset to normal operation mode.

System Administrator’s Guide

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3Com NSR-ORA V3.2 manual Automatic Recovery Crash Recovery

NSR-ORA V3.2 specifications

The 3Com NSR-ORA V3.2 is a versatile networking solution designed to enhance connectivity and streamline data management across various enterprise environments. With the rapid evolution of digital communication, 3Com recognized the need for a robust system that caters to the demanding requirements of today's businesses. The NSR-ORA V3.2 is specifically engineered to provide optimal performance, scalability, and reliability.

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