Oracle Database Corruption Recovery Solution for Block Corruptions
Various factors can cause database files to be corrupted or lost. This informative article provides a recovery solution to minimize the loss in case of Oracle database corruption.
Block corruption is a common cause of database outages. Database blocks become corrupted when their content changes from what Oracle database (.dbf) expects to detect. If you don’t prevent or repair block corruption, your database may become inoperable and your key business data may be lost.
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Why Oracle Database Block Corruption Occurs?
Data block corruption can occur every time data changes and can be traced back to hardware and software issues. Problems with any or all of the following components can corrupt data blocks:
- Hard Drive Failure
- Disk Controller Issues
- Operating System Failure
- Storage Area Network (SAN) Issues
- Storage Device Failure
What is Physical and Logical Corruption?
Oracle database corruption can be categorized as physical and logical corruption.
Physical Corruption of the block appears as an invalid checksum or header, or if the block contains all zeros. In that case, the database does not recognize the block as a valid Oracle block, regardless of its content. Physical corruption is also known as media corruption.
Logical Corruption occurs when a block of data has a valid checksum, etc., but the content of the block is logically inconsistent. Logical block corruption can also occur if the structure below the beginning of the block (below the block header) is corrupted.
In this case, the block checksum is correct, but the block structure may be corrupted. Logical corruption can also occur if a write is lost. In this case, the version of the block sent to disk has not actually been written. As a result, the version of that block on Disk Buffer cache version. Write losses are usually caused by a bug in the operating system or hardware.
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Prevention of Oracle Database Corruption
Get Oracle database corruption recovery solutions in detail:
Periodically Check for Media Failure Issues:– It can be difficult to pinpoint the root cause of database corruption. Look for alerts or warning messages about physical media issues to prevent loss. For example, if there is a problem mounting the media, it may indicate a problem that may corrupt the file. Also, pay attention to abnormal noise and turn off the power.
Use system utilities to identify and fix device problems. Watch out for messages like “bad sectors“. This can be the main reason why the database keeps getting corrupted.
Unmount Attached Devices:– The safest way to remove an Oracle file from a multi-user device is to unmount it to avoid data corruption. If you can’t unmount it, shut down your computer until you find the cause of the problem.
Oracle Database Backup:– You can restore files from a backup in case the database is lost. You can identify the restored files by taking a backup. Check the file size and last modified time to see if any files are missing. Consider having separate external and system backups. If the file gets corrupted, you have to resort to something else.
Oracle Repair Utilities:– You can use the built-in repair tools to recover damaged Oracle database files. However, it is recommended that you first copy the files before repairing them, as the process may overwrite your data. Instead of solving the problem, it can make the situation worse, especially if the media has existing mechanical problems.
Oracle offers a variety of tools for Oracle database corruption recovery solution, including:
- Oracle Data Guard: Protects your company’s database in the event of disaster or corruption.
- Data Recovery Advisor: Diagnose data loss or corruption and perform repairs.
- Oracle Flashback: Restores a database table or row to a previous state.
- Oracle Recovery Manager: Backup and recovers the Oracle database.
- Oracle Secure Backup: Backup all file system data and Oracle database files in a secure manner.
Summing Up
Data block corruption is an unfortunate Oracle occurrence, but Oracle has a secure and extensive set of tools to protect and recover enterprise data. Performing regular corruption checks with software such as Oracle Data Guard or Oracle Recovery Manager can help you address data block corruption issues.
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