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Oracle Data Guard Ensuring Disaster Recovery for Enterprise Data. Enterprise Technology Centre. Introducing Oracle Data Guard. Oracle Data Guard is the most effective and comprehensive Disaster Recovery solution available today for enterprise data.
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Oracle Data Guard Ensuring Disaster Recovery for Enterprise Data Enterprise Technology Centre
Introducing Oracle Data Guard Oracle Data Guard is the most effective and comprehensive Disaster Recovery solution available today for enterprise data
Oracle’s High Availability (HA) Solution Stack Real Application ClustersContinuous Availability for all Applications System Failure Data GuardZero Data Loss UnplannedDowntime Data Failure& Disaster Flashback QueryEnable Users to Correct their Mistakes Human Error Dynamic ReconfigurationCapacity on Demand without Interruption SystemMaintenance PlannedDowntime Online RedefinitionAdapt to Change Online Data Maintenance
Oracle Data Guard Focus • Data Failures & Site Disasters: • Data Protection • Data Availability • Data Recovery • Data is the core asset of the enterprise! • Eliminates and reduces downtimes that could occur because of human errors & planned maintenances
What Is Oracle Data Guard? • Database software infrastructure that automates the creation and maintenance of a duplicate, or standby copy, of the production (or primary) database • If the primary database becomes unavailable (disasters, maintenance), the standby database can be activated and can take over the data serving needs of the enterprise
How Does It Work? • As primary database is modified, redo data is propagated to standby databases • Standby databases kept synchronized with primary • Primary database is open and active; standby database is either in recovery or open read-only / read-write • Standby database can be transitioned to the primary role as necessary
Production Database Network Broker Logical Standby Database Transform Redo to SQL Open for Reports SQLApply Optional Delay Additional Indexes & MVs Oracle Data Guard Architecture Physical Standby Database Sync or Async Redo Shipping Backup Redo Apply Optional Delay
Data Guard Redo Apply Data Guard Broker Physical Standby Database Primary Database Optional Delay Backup Network Redo Apply Sync or Async Redo Shipping • Physical Standby Database is a block-for-block copy of the primary database • Uses the database recovery functionality to apply changes • Can be opened in read-only mode for reporting/queries • Can also perform backup, offloading production database
Data Guard SQL Apply Additional Indexes & Materialized Views Data Guard Broker Primary Database Logical Standby Database Optional Delay ContinuouslyOpen for Reports Network Sync or Async Redo Shipping Transform Redo to SQL and Apply • Logical Standby Database is an open, independent, active database • Contains the same logical information (rows) as the production database • Physical organization and structure can be very different • Can be queried for reports while logs are being applied via SQL • Can create additional indexes and materialized views for better query performance
Read-Only / Read-Write Reporting Backups Tape Standby Database Standby Databases Are Not Idle Standby Server Standby database can be used to offload the primary database, increasing the ROI
Standby Site Primary Site Standby Database Production Database Optional Delayed Apply Protection from Human Errors and Data Corruptions • The application of changes received from the primary can be delayed at standby to allow for the detection of user errors and prevent standby to be affected
Switchover and Failover • Primary and Standby role transitions • Switchover • Planned role reversal • No database reinstantiation required • Used for maintenance of OS or hardware • Failover • Unplanned failure (e.g. disasters) of primary • Primary database must be reinstantiated • Initiated using simple SQL / GUI interface
Flexible Data Protection Modes Balance cost, availability, performance, and transaction protection
Maximum Protection Mode • Highest level of data protection • Enforces protection of every transaction • If last standby is unavailable, processing stops at primary • Good for financial systems where no data loss is acceptable ALTER DATABASE SET STANDBY TO MAXIMIZE PROTECTION;
Maximum Availability Mode • Enforces protection of every transaction • If last standby is unavailable, processing continues at primary • When it is re-available, synchronization is automatic ALTER DATABASE SET STANDBY TO MAXIMIZE AVAILABILITY;
Maximum Performance Mode • Highest level of performance • Protects from failure of any single component • Least impact on production system • Useful for applications that can tolerate some data loss ALTER DATABASE SET STANDBY TO MAXIMIZE PERFORMANCE;
Oracle Data Guard Broker • Distributed management framework that automates and centralizes the creation, maintenance, and monitoring of Data Guard configurations • Management operations can be performed locally or remotely through the Broker's easy-to-use interfaces: • GUI-based Oracle Data Guard Manager • Data Guard command-line interface
Data Guard Manager • Simple, easy-to-use management and monitoring interface
Local and Remote Standby Databases • Oracle Data Guard configuration can support both local and remote standby databases • Local standby database • Appropriate for highest data protection modes • LAN links are cheap, reliable, have high bandwidth and low latency • Switchover operations are very fast • Remote standby database • Best solution for disaster recovery • WAN links are generally more expensive, less reliable, have lower bandwidth and higher latency than LAN links • Suitable for highest performance asynchronous data protection mode
Standby Site A Standby Site B Synchronous transport LAN attached Used to offload backups First choice for switchover candidate Primary Site Standby Database Standby Database Synchronous transport LAN attached Used to offload reporting Primary Database Standby Site C Standby Database Asynchronous transport WAN attached Delayed apply Provides DR and data protection Usage Example
Oracle Data Guard and Real Application Clusters • Data Guard and Real Application Clusters are complementary and should be used together • Real Application Clusters provides high availability • Provides rapid and automatic recovery from node failures or an instance crash • Provides increased scalability • Data Guard provides disaster protection and prevents data loss • By maintaining transactionally consistent copies of primary database • Protects against disasters, data corruption and user errors • Does not require expensive and complex HW/SW mirroring
Data Guard and Remote Mirroring • Oracle Data Guard’s integrated disaster recovery solution involving standby databases is often preferred to remote disk mirroring • Better network efficiency • Better resilience and data protection • Higher ROI (backup, reporting servers, etc) • Remote mirroring (ie. HP Continuous Access) can be used in combination with standby databases to protect non-database data