Tuesday, March 19, 2013

Overview of Oracle Data Guard

Oracle Data Guard provides high availability solutions to prevent data loss in the event of disaster. It also provides set of services to manage standby database so that if production database becomes inaccessible due to corruption or outage, Data Guard can use standby database by switching its role with production database to minimize the downtime. The main motive of Data Guard is to provide maximum data protection and availability.

Data Guard Configuration
Data Guard has one primary (production) database and one or more standby databases. Primary database is the main database that is accessed frequently by your application and standby database is the exact copy of your primary database which is used when primary database fails. There are two type of standby database:
  1. Physical standby database: Physical standby database is an exact physical copy of the primary database. It is mostly used for disaster recovery.
  2. Logical standby database: It store same logical information as primary database but its physical structure could be different. Logical standby database is used for many purposes like disaster recovery, resolving user queries and reporting purpose.
Type of protection mode in Data Guard: There are three types of protection modes in Data Guard. These modes are designed according to different requirement like some organizations can't afford to lose their precious data and for some organizations database availability is more important. So organizations can choose the mode that suits their needs.
  1. Maximum protection: It ensures no data loss in the situation of failure of primary database. The primary database must be shutdown if a fault occurs to prevent it from writing to standby database. One major drawback is slow response time of primary database.
  2. Maximum availability: It ensures maximum data protection and availability of primary database. Unlike maximum protection mode there is no need to shutdown the primary database even if a fault occurs. The drawback is that data loss may occur if network fails.
  3. Maximum performance: It also ensures maximum data protection without affection the primary database performance. Data loss may occur in this mode.
Advantages of Data Guard
  1. Provides High Availability solutions: Data Guard provides high availability solutions to prevent data loss in case of disaster recovery.
  2. Protect data: Data Guard provides complete data protection by ensuring that no loss will occur even in the event of disaster. Logical or physical corruption errors that can damage primary database are easily resolved.
  3. Protection modes: Data guard provides three modes that ensure maximum data availability, maximum data protection and maximum performance.
  4. Simple interface: Data Guard broker provides highly interactive and user friendly interface to perform operational and management tasks.
  5. No separate installation: Data Guard is a feature of Oracle Database Enterprise Edition therefore no separate installation is required.

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