Monday, January 28, 2013

How to prevent data against block corruption in Oracle?

Data block corruption is a common scenario in Oracle. It is said to be corrupted when its contents become inconsistent or it is not in a proper format (Oracle Database Format). Block corruption can result in excessive data loss if not identified or repaired on time. It can affect your whole database making it unusable. However you still can prevent corruption using advanced techniques provided by Oracle.

Prevention techniques: There are many techniques provided by Oracle that help in prevent corruption. You obviously can't prevent all block corruption but using these technique you can address most of them.
  1. Oracle Data guard: It provides high availability solutions to protect data against corruption. Data guard maintains two databases one is primary and another is standby (secondary database). In standby database it stores the physical copy of primary database and also updates it whenever there is any change in production database. It also detects physical corruption and prevents it from impacting the database.
  2. Data Recovery Advisor: It automatically detects corruption and provides appropriate repair options. Data Recovery advisor detects and repair corruption in primary, secondary and snapshot database. You can use Data Recovery Advisor to repair a down database, block corruptions, data dictionary corruptions and undo corruptions. 
  3. Oracle Recovery Manager: RMAN provides a highly efficient backup and recovery strategy for Oracle database. The best thing with RMAN is that it knows which file needed a backup. It protects your data against media and block corruption. During backup, it detects block corruption and repairs it, if needed. To protect data against block corruption use the CHECK LOGICAL option of RMAN.
  4. Oracle Secure Backup: It provides tape backup protection for Unix, Linux, Windows and other file systems. Oracle secure backup is faster (25-40%) than any other backup and also came at a reasonable cost.
  5. Oracle Flashback: This technology provides efficient data recovery solutions to reduce recovery time of a damaged database from hours to minutes. It supports recovery of row, table, transaction and whole database.
These are the most effective techniques to prevent data against block corruption. However, if even after using these techniques your database becomes corrupt then opt for a good 3rd party Oracle database recovery tool.

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