Information about Oracle Data Guard
The software which Oracle Corporation markets as Oracle Data Guard forms an extension to the Oracle RDBMS. It aids in establishing and maintaining secondary "standby databases" as alternative/supplementary repositories to production "primary databases".
Oracle Corporation provides both GUI and command-line tools for managing Data Guard configurations.
Data Guard supports both physical standby and logical standby sites. Oracle Corporation makes Data Guard available only as a bundled feature included within its "Enterprise Edition" of the Oracle RDBMS.[1]
With appropriately set-up Data Guard operations, DBAs can facilitate failovers or switchovers to alternative hosts in the same or alternative locations.
Logical standby databases re-apply SQL transactions generated on their primary node; thus physical structures and organization. As of Oracle release 11g Data Guard may operate across different "CPU architectures, operating systems ... operating system binaries (32-bit/64-bit), and Oracle database binaries (32-bit/64-bit)."[2] Users (under certain conditions) can write to as well as read from logical standby databases; and such databases can switch in function to and fro between primary and standby roles.
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).[3]
Once the archived redo logs have arrived, other processes (such as an ARCH (Archiver process), an MRP (Managed Recovery Process), and/or an LSP (Logical Standby Process)) may set about applying the log contents to the standby database..
Oracle Corporation provides both GUI and command-line tools for managing Data Guard configurations.
Data Guard supports both physical standby and logical standby sites. Oracle Corporation makes Data Guard available only as a bundled feature included within its "Enterprise Edition" of the Oracle RDBMS.[1]
With appropriately set-up Data Guard operations, DBAs can facilitate failovers or switchovers to alternative hosts in the same or alternative locations.
Configurations
A physical standby database attempts to replicate the exact structure and layout of its primary database across the Oracle Net network layer. It can function either in archiving ("recovery") mode or in read-only mode, but not in both modes at the same time. It can become a standalone database when required, but needs rebuilding before reverting from standalone to standby functionality.Logical standby databases re-apply SQL transactions generated on their primary node; thus physical structures and organization. As of Oracle release 11g Data Guard may operate across different "CPU architectures, operating systems ... operating system binaries (32-bit/64-bit), and Oracle database binaries (32-bit/64-bit)."[2] Users (under certain conditions) can write to as well as read from logical standby databases; and such databases can switch in function to and fro between primary and standby roles.
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.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).[3]
Once the archived redo logs have arrived, other processes (such as an ARCH (Archiver process), an MRP (Managed Recovery Process), and/or an LSP (Logical Standby Process)) may set about applying the log contents to the standby database..
Advantages
Data Guard provides high availability for a database system. It can also reduce the human intervention required to switch between databases at disaster-recovery ("failover") or upgrade/maintenance ("switchover") time.References
1. ^ [1] Data Guard Concepts and Administration, 11g Release 1 (11.1); Section 2.3.2: "Oracle Software Requirements" Retrieved 2007-10-01
2. ^ [2] Data Guard Concepts and Administration, 11g Release 1 (11.1); Section 2.3.1 "Hardware and Operating System Requirements" Retrieved 2007-10-01
3. ^ Oracle-Base site summary of Data Guard, retrieved 2007-09-05; Oracle Corp version 11.1 documentation links, retrieved 2007-09-05.
2. ^ [2] Data Guard Concepts and Administration, 11g Release 1 (11.1); Section 2.3.1 "Hardware and Operating System Requirements" Retrieved 2007-10-01
3. ^ Oracle-Base site summary of Data Guard, retrieved 2007-09-05; Oracle Corp version 11.1 documentation links, retrieved 2007-09-05.
Oracle Corporation
Public (NASDAQ: ORCL )
Founded California, USA (1977)[1]
Headquarters Redwood Shores, California, USA
Key people Lawrence (Larry) J. Ellison, CEO
Jeffrey O. Henley, Chairman
Safra A.
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Public (NASDAQ: ORCL )
Founded California, USA (1977)[1]
Headquarters Redwood Shores, California, USA
Key people Lawrence (Larry) J. Ellison, CEO
Jeffrey O. Henley, Chairman
Safra A.
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Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle), a relational database management system (RDBMS) software product released by Oracle Corporation, has become a major feature of database computing.
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A database management system (DBMS) is computer software designed for the purpose of managing databases. Typical examples of DBMSs include Oracle, DB2, Microsoft Access, Microsoft SQL Server, PostgreSQL, MySQL, FileMaker and Sybase Adaptive Server Enterprise.
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graphical user interface (GUI) is a type of user interface which allows people to interact with a computer and computer-controlled devices which employ graphical icons, visual indicators or special graphical elements called "widgets", along with text, labels or text
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command line interface or CLI is a method of interacting with an operating system or software using a command line interpreter. This command line interpreter may be a text terminal, terminal emulator, or remote shell client such as PuTTY.
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Product bundling is a marketing strategy that involves offering several products for sale as one combined product. This strategy is very common in the software business (for example: bundle a word processor, a spreadsheet, and a database into a single office suite), and in the fast
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Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle), a relational database management system (RDBMS) software product released by Oracle Corporation, has become a major feature of database computing.
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A database administrator (DBA) is a person who is responsible for the environmental aspects of a database. In general, these include:
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- Recoverability - Creating and testing Backups
- Integrity - Verifying or helping to verify data integrity
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Failover is the capability to switch over automatically to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active server, system, or network.
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Switchover is the capability to manually switch over from one system to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active server, system, or network.
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network layer is the third layer out of seven in OSI model and the third layer out of five in TCP/IP model. In the TCP/IP reference model it is called the Internet layer.
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In the Oracle RDBMS environment, redo logs comprise files in a proprietary format which log a history of all changes made to the database. Each redo log file consists of redo records.
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High availability is a system design protocol and associated implementation that ensures a certain absolute degree of operational continuity during a given measurement period.
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database is a structured collection of records or data that is stored in a computer system so that a computer program or person using a query language can consult it to answer queries. The records retrieved in answer to queries are information that can be used to make decisions.
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The term upgrade is most often used in computing and consumer electronics, generally meaning a replacement of hardware, software or firmware with a newer version, in order to bring the system up to date.
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Maintenance may refer to:
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- Maintenance of an organism
- Maintenance, repair and operations
- Maintenance of way
- Car maintenance
- High maintenance
- Preventive maintenance
- Software maintenance
- Child support or alimony, also called spousal support
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