Oracle Data Guard: Difference between revisions

Revision as of 16:02, 3 May 2007

Revision as of 08:17, 12 August 2007

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The software which [[Oracle Corporation]] markets as '''Oracle Data Guard''' forms an extension to the [[Oracle database]] [[DBMS|management system]]. It aids in establishing and maintaining secondary "[[standby database]]s" as alternativesalternative/supplementary repositories to production "primary databases".

Oracle Corporation provides both [[graphical user interface|GUI]] and [[command line interface|command-line]] tools for managing Data Guard configurations.

Data Guard supports both '''physical standby''' and '''logical standby''' sites. It runs under most Oracle editions, but not under Oracle Express Edition (XE).

With appropriately set -up Data Guard operations, [[database administrator|DBA]]s can facilitate [[failover]]s or [[switchover]]s to alternative hosts in the same or alternative locations.

== Operation ==

A primary site which has an archived redo log to transfer invokes the '''RFS (remote file server)''' background process within the Oracle instance running on a standby host. The RFS process then performs the task of receiving archived redo logs sent from the primary database. Once such logs have arrived, other processes (an ARCH (Archiver process), MRP (Managed Recovery Process), LSP (Logical Standby Process)) may set about applying their contents to the standby database..

Alternatively, a supplementary mechanism may transfer the archived redo logs. On the standby database a '''Fetch Archive Log (FAL)''' client monitors for gaps in the sequence of received logs. If it finds a gap, it may invoke one or more Fetch Archive Log (FAL) servers to run on the primary database to forward the missing item(s).<ref>

== Advantage ==

http://www.oracle-base.com/articles/9i/DataGuard.php

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Once the archived redo logs have arrived, other processes (an '''ARCH (Archiver process)''', '''MRP (Managed Recovery Process)''', '''LSP (Logical Standby Process)''') may set about applying their contents to the standby database..

== Advantages ==

Data Guard provideprovides high availability offor thea database system. andIt can also reduce the reduces human intervention required to switch between [[databases]].

== References ==

{{Reflist|1}}

Data Guard provide high availability of the system and reduces human intervention to switch between [[databases]].

[[Category:Database software stubs]]

[[Category:Oracle software]]