Oracle Dataguard
Oracle Data Guard is an extension of the Oracle database management system , which allows the operation of a standby database . With Data Guard it is possible to send all data changes to a spatially separated database. This can then be scheduled ( switchover ) or in the event of a failure of the primary database ( failover ).
It is possible to connect both physical and logical standby databases to the primary database. The standby databases can be operated in real time or with a time delay (e.g. to rule out human errors). Switching can take place automatically. An observer is used to monitor the Data Guard configuration externally. If the primary database fails, the observer initiates a failover to the second database, which then takes over operation.
The primary database can also be relieved by running queries on the standby database, but this option is chargeable ("Active Data Guard"). With Oracle Database 12c, additional configuration options were added for distant standby systems. These include far sync and zero data loss.
It is controlled using a graphical user interface or a command line-oriented tool (Data Guard Control).
literature
- Andrea Held: Oracle 10g high availability. The fail-safe database with Real Application Cluster (RAC), Data Guard and Flashback . Addison-Wesley, Munich 2003, ISBN 3-8273-2163-8 .
- Andrea Held, Oracle 11g - New Features , Language: German, Hardcover - Hanser-Verlag, Munich, Publication Date: May 2008, ISBN 3-446-41198-4
- Matthew Hart, Scott Jesse: Oracle Database 10g. High availability with RAC, Flashback & Data Guard . Osborne / McGraw-Hill (Oracle Press), New York 2004, ISBN 0-07-225428-9 (English).