The procedure of data recovery from Oracle databases discussed in this session is inclusive of the hardware crashes experienced by the server disk drive. Hence it is vital that you restore the disk drive working conditions before making any attempt to restore the Oracle database. The first section deals exclusively with the software and hardware procedures needed for correcting the logical and physical damages suffered by the server disk drive. In the second section you will be able to read about the systematic procedures involved in restoring database objects in a step by step approach.
As you are aware, the disk drive used to host the Oracle databases in the Windows server may consist of RAID support. You can take the help of professional hardware consultants and database experts to choose the best of hardware setup and disk drive systems for enabling smooth management of Oracle database management. We offer complete support to all your database management needs related to installation, configuration, backup and recovery, system support as well as front end development for Oracle databases.
The process of hardware restoration in case of oracle database servers will have to be done with the help of OEM software tools and certified hardware toolkits only. If you are running windows enterprise server, you may be able to restore the logical errors though remote installation from the backup server or replication server. If that facility is not available, then you may have to opt for an onsite hardware technician to set right the hardware issues and restore the operating system along with network settings.
If you happen to run other applications on the Oracle database server and store their related files and folders, you need to recover them also. In case you run regular backup of your oracle databases onto external media or a backup sever, you don’t need to worry about recovering those files from the crashed disk drive. Once you have reinstated the hardware and reinstalled the OS and network settings, you just need to restore the Oracle database completely from the backup media. Before that you need to install the Oracle server software onto the disk in case you are unable to recover that. Once you are through with these basic level works, it is possible for you to start recovering the Oracle database from the back up in simple steps.
Oracle database recovery
Open the backup/recovery menu from the Oracle application tools. Before doing this you need to make sure that no active users are connected to the database. Once all; the users have logged out, you need to lock the Oracle database in the server so that no one will be able to access it by accident during recovery process. The best practice is to deploy a technical database expert who can perform this task for you.
The recovery menu will prompt the technician to enter the last backup from which he wants to restore the data for recovery. Once he has specified the backup file, the system will prompt for performing complete recovery or table space recovery. Once he selects the complete restore, the system will restore all the database objects from that backup. Now the system needs to be restarted once to complete the procedure.
Preventive measures help you in being prepared for the disaster or take actions to avoid their occurrence. Some of the simple procedures which you could follow in your everyday data transactions and database management, along with disk management will be able to avoid many catastrophic events.
Diagnosis of block data corruptions
Data-guard is one of the most recommended systems for diagnosing the physical corruptions in the Oracle database. The system basically works in two methods of process halting and rollback. When a corrupt block is found in the database entry point, the system blocks further processes from happening. The Data-guard system offers a Grid system through this process can be automated. If the option for grid system is not available with you, then it has to be done manually. For that you have to conduct a query on the view related to the V$DATAGUARD_STATS. Once this query is processed by the system, it will return the time and process lag in applying the Commitment of transactions and Transport of data from the client system onto the server database. You need to consistently observe this output after every 30 minutes interval. With is command you will be able to read the control file located in the database server.
There is another view which you can query to get the status of Rollback procedures that have been applied to the transactions, when the commit command is encountered with a blocking of database entry. This command is V$RECOVERY_PROGRESS. Both the commands can be passed onto the database server from the Query window. Three of the critical elements that you need in your Oracle RMAN for the successful monitoring of transactions are listed below.
The database recovery-catalog is another file in which the repository details are stored in the system. This will be used by RMAN to control and monitor the recovery procedures in case of control files deletion. The catalog also holds stored procedures which are sequences of RMAN and SQL+ commands used for data recovery and backup procedure management. This is said to be more convenient than working with commands, since the stored procedures stay at the target database and get executed within the server space, while the SQL commands will have to pass the control from the client to the server.
Flash recovery area
This is the region where disk space management and file handling procedures are featured, in relation to the procedures related to recovery and back up. The technician will be able to initialize the recovery by issuing the commands DB_RECOVERY_FILE_DEST and DB_RECOVERY_FILE_DEST_SIZE. These two commands help in optimization of backup and recovery processes.
It is in fact a software application which is responsible for monitoring and controlling the activities related storage and backup devices.
Channels are the Input /Output paths for the backup and restore operations. They are configured by RMAN with the help of CONFIGURE commands.