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Oracle Maximum Availability Architectures (MAA)
Steve Woody, CommitDBA President
February 9, 2016
Oracle has long been a leader with enterprise database High Availability (HA) and Disaster Recovery (DR) solutions. Oracle’s Maximum Availability Architecture (MAA) provisioning which includes HA and DR is essential with today’s next generation application processing requirements for 24x7 availability. With e-commerce, web services, mobile apps and enterprise application software (EAS) evolving rapidly and data growth expanding at record pace, data assurance, data accuracy and data availability is critical.
Oracle has evolved a number of failsafe MAA options over the years with some complimenting other MMA solutions. The entrance of Cloud computing has also provided a new form of MMA option. Organizational Recovery Point and Time Objectives (RPO/RTO) can be met with one or more MMA solutions as described in this article.
So let’s take a look at what are the current Oracle specific MMA solutions.
1. Oracle Real Applications Clusters (RAC)
Oracle Real Application Clusters (Oracle RAC) is a clustered version of Oracle Databases that is based on a comprehensive high-availability stack which is a key component of Oracle’s Maximum Availability Architecture high availability (MAA-HA). Oracle RAC provides customers with the highest database availability by removing the single database server as a single point of failure. For instance, Oracle (Shared) database instances on nodes within a cluster will continue run if one of the node goes down.
The Oracle Clusterware technology itself transforms a server farm into a cluster. A cluster is defined as a group of independent, but connected servers, cooperating as a single system where multiple Instances can be connected to a centralized database within the cluster. Oracle RAC enables customers to continue processing database workloads in the event of a server failure, and reduces cost of downtime by reducing the amount of time databases are taken offline for planned maintenance operations. However, even clustered databases (RAC) as a high availability option, provides only a single point of failure. To eliminate a single point of failure we would optimally add to MAA Oracle Data Guard or GoldenGate as are discussed below.
2. Oracle Data Guard
Oracle Data Guard (ADG) provides the management, monitoring, and automation software to create and maintain one or more synchronized standby databases that protect data from failures, disasters, errors, and corruptions. Data Guard provides Maximum Availability Architecture for high availability and disaster recovery requirements (MAA-HA-DR). Data Guard provides a solution to single point of failure by deploying this independent copy (standby) to a second and possibly additional physical locations.
Both synchronous (zero data loss) and asynchronous (near-zero data loss) configurations are supported. Both manual and automatic (hot) failover of production to a standby database if necessary are available options for the DBA. Also, there are two types of standby databases. The first (physical) uses redo log applies (Redo Apply) which maintains exact replications of the primary databases. The second (logical) maintains a replica of the primary database using SQL Apply and the ROWIDs are different between the primary and standby database. A superset called Active Data Guard allows you to query and run reports in real time on the standby server that has been sync’d up with production server.
3. Oracle GoldenGate
Oracle GoldenGate is a full featured product with many purposes that provides heterogeneous data integration, encryption and distribution solutions, but also has a replication component within its Maximum Availability Architecture for high availability and disaster recovery (MAA-HA-DR). Similar to Data Guard, GoldenGate provides a solution to single point of failure by deploying this independent copy (standby) to a second and possibly additional physical locations. GoldenGate also provides additional functions including multi-master replications, hub and spoke deployment and data transformation. In addition, GoldenGate also supports replication between heterogeneous hardware and database environments where Data Guard does not.
Synchronous (zero data loss) configuration is supported by GoldenGate similarly to Active Data Guard (logical) replication where Oracle databases are represented in both the primary and replica. For heterogeneous replication, GoldenGate captures primary database changes by reading the redo records from disk, and transforming those records into a platform independent trail file to the target database. GoldenGate maintains a logical replica by converting the trail file into SQL and applying SQL to the target database.
4. Zero Data Loss Recovery Appliance
Oracle’s Zero Data Loss Recovery Appliance (e.g. Recovery Appliance) eliminates data loss exposure while reducing data protection overhead in production. Recovery Appliance is Oracle’s engineered hardware system within its Maximum Availability Architecture for disaster recovery (MAA-DR). Recovery Appliance was specifically designed for easy and quick data recovery since it is directly integrated with the Oracle RDBMS.
The Recovery Appliance provides similar levels of data protection as in Data Guard for databases but does not necessarily require Data Guard’s fast failover and query offload capabilities. Oracle redo logs within the Oracle database can be sent directly (real-time) from in-memory log buffers to the Recovery Appliance. Only changed data is transferred which is compressed. All backup data and redo blocks are automatically validated as they are received by the Recovery Appliance. Continuous database-aware validation ensures data integrity and database recovery to any point in time.
5. Oracle Cloud
Oracle provides enterprise cloud services for Maximum Available Architecture utilizing both cloud backup for high availability cloud backup for disaster recovery with Data Guard or GoldenGate (MAA-HA-DR). Oracle Data Guard and GoldenGate enable standby databases in Oracle Cloud for data recovery and high availability as described previously in item 2 and 3. The big advantage for utilizing Data Guard/GoldenGate in the cloud is that you do not have to establish the standby in another facility. All replication and rollover is provisioned to the cloud when requirements dictate that the DBA does so.
Oracle Cloud’s also offers customers the ability to ship Oracle database backups to the cloud. The advantages include enhanced performance, redundancy, secure and inexpensive Oracle database backup services to the cloud while off-loading that responsibility from on-premise. The Oracle Cloud Backup is part of the Maximum Availability Architecture for Disaster Recovery (MAA-DR). Oracle’s standard backup utility Recovery Manager (RMAN) is configured to for cloud provisioning and works in a similar fashion to on-premise RMAN backups.