Oracle Data Guard is an extension to Oracle Relational Database Management System (RDBMS) which helps in the establishment and maintenance of standby databases. Oracle provides GUI and command-line tools to manage Data guard configurations. Oracle Data Guard ensures the availability, data security and data recovery for enterprise data that provides comprehensive services such as create, monitor, maintain and manage one or more databases. The most efficient feature of data guard is to maintain standby databases that keep the copies of production database, so if the production database is unavailable then Data guard can switch to any standby database to the production role which decreases the downtime associated with the unplanned outage. Data guard helps administrators to improve the production database performance by providing resource backup and reporting operations to the standby system. Oracle Data Guard is supported by XML type data that are stored in binary format and object relational format, hence it imposes higher redo compatibility.
Data Guard Configuration
Oracle Data Guard comprises of three database model which functions either in primary database role or in standby database role.
Physical Standby: This provides identical copy of the primary database which supports on disk database structure on a block-for-block basis. The biggest feature that physical standby database includes is the option of Redo Apply that makes it able to synchronize with primary database. Redo Apply helps in recovering of data that is received from primary database and applies redo on physical standby database.
Logical Standby: It contains the logical information of database that are same as production database. Here the logical standby database synchronizes with primary database through SQL Apply. SQL apply transforms the redo received data from primary database to SQL statements and these statements get executed on standby database. In addition to disaster recovery, logical standby database is also used for other business purpose. It serves the queries and reporting services and also helps in up-gradation of Oracle database software.
Active Data Guard: It is an additional facility to extend the functionality of Oracle Data Guard in Oracle 11g configurations that allows read only access over the physical standby node. It comprises of automatic block repair and physical standby that makes it unique and reliable.
Data Guard Benefits
Oracle Data Guard actually provides so many functionalities that helps to establish a good reputation in IT industries. Following are the beneficiary aspects associated with Oracle Data Guard
- Data guard provides an effective management of database recovery and data availability that increases the failover capabilities to minimize the downtime of unplanned outage.
- Data guard provides security over data corruption and user errors and also ensures that there will be no data loss. It resolves the problem of logical corruption that cause the damage of primary database.
- The standby database is featured with redo option which helps in data backup, reporting, queries and also reduces the work overload of primary database as it saves CPU and I/O cycles.
- It detects the gap that causes due to the connection loss between primary and standby databases and redo them to re-establish the connection with the help of archived log files.