|Oracle® Real Application Clusters Deployment and Performance Guide
10g Release 1 (10.1)
Part Number B10768-01
This chapter introduces Oracle Real Application Clusters (RAC) application deployment and performance by explaining the main points to remember when you deploy applications on RAC. This chapter includes the following topics:
Storage for RAC datafiles must be shared storage—When you install RAC, use a Cluster File System for datafile storage when available.
Create your database with the Database Configuration Assistant (DBCA).
Define services for your environment with the DBCA and administer them with Oracle Enterprise Manager and the Server Control (SRVCTL) Utility.
Use the Server Parameter File (SPFILE)—The SPFILE should be located on either a cluster file system file or on a shared raw device.
Use Automatic Undo Management.
Use Automatic Segment-Space Management.
Automatic Database Diagnostic Monitor (ADDM) to reduce the effort required to tune Oracle systems.
See Also:Oracle Real Application Clusters Installation and Configuration Guide for more information about configuring these features for Oracle Real Application Clusters 10g
The Oracle features described in this section enhance the performance of your RAC environment. The features discussed in this section are:
Depending on your hardware platform, you can store Oracle homes and Oracle datafiles on a cluster file system. Cluster file systems are simpler to configure and manage than raw device storage. Cluster file systems also offer scalable, low latency, highly resilient storage that significantly reduces costs.
The advanced storage features of Oracle Automatic Storage Management greatly enhance manageability for RAC just as with single instance Oracle. Other storage features include Oracle-managed files, automatic segment-space management, and automatic undo management. Refer to the Oracle database documentation for more information about using storage management features.
With Oracle Database 10g, application workloads can be defined as services so that they can be individually managed and controlled. You can create a service for each separate application or for major components within a complex application. Once created, you can define where and when the service runs. Your entire database workload can be separated into a few services, each of which can be managed independently, reducing your need to manage individual users or sessions for many tasks.
In a RAC database, you can use services to maximize the value of your cluster's processing resources. Each service can be assigned to one or more instances for normal startup (preferred), depending on its processing requirements. Additionally, you can define one or more alternate (available) instances that a service can use should one of its assigned (preferred) instances become unavailable.
On both cluster and non-cluster environments, performance metrics can be tracked by service using the Automatic Workload Repository (AWR). Thresholds on performance metrics can be set to automatically generate alerts should these thresholds be crossed. Services can be mapped to Resource Manager consumer groups to provide more fine-grained resource allocation controls such as placing limits on CPU consumption. Other Oracle tools and facilities such as Job Scheduler, Parallel Query, and Oracle Streams Advanced Queuing can also use services to manage their workloads.
This section introduces the following high availability features:
Oracle Real Application Clusters 10g introduces a complete, integrated clusterware management solution on all Oracle Database 10g platforms. This clusterware functionality provides all the features required to manage your cluster database including node membership, group services, global resource management, and high availability functions. The clusterware facility is called Cluster Ready Services (CRS) and you install it as part of the RAC installation process. Oracle database features such as Oracle 10g services use the underlying CRS mechanisms to provide their capabilities. Oracle also continues to support select third-party clusterware products on specified platforms.
High availability configurations have redundant hardware and software that maintain operations by avoiding single points-of-failure. When outages occur, CRS relocates the processing performed by the inoperative component to a backup component. Oracle's recovery processes quickly re-master resources, recover partial or failed transactions, and rapidly restore the system.
You can combine many Oracle products and features to create highly reliable computing environments. Doing this requires capacity and redundancy planning. In addition, consider your overall system costs and your return on investment. There are also other practical considerations such as selecting the appropriate hardware and deciding whether to use idle machines that are part of your high availability configuration.
This section describes the following additional high availability solutions:
The connection load balancing feature automatically distributes connections among active instances. Connection load balancing does this based on the workload of each node and instance in a cluster. RAC and Cache Fusion combined with connection load balancing supports all types of applications without application or data partitioning.
Recovery Manager (RMAN) is an Oracle tool that you can use to backup, copy, restore, and recover datafiles, control files, SPFILEs, and archived redo logs. You can invoke RMAN as a command line utility or use in Oracle Enterprise Manager.
A best practice is to configure RMAN so that all instances can access all the archive log threads throughout your cluster database. In the event of media recovery, the recovering instance requires access to all of the archived redo log threads. Therefore, simplify media recovery administration by ensuring that a recovering instance can access a local copy of the archive log threads from all of the instances in your cluster database.
See Also:Oracle Real Application Clusters Administrator's Guide for details about configuring RMAN for use with RAC and Oracle Database Backup and Recovery Advanced User's Guide for detailed information about RMAN
Oracle Data Guard works with standby databases to protect your data against errors, failures, and corruptions that might otherwise destroy your database. Data Guard protects critical data by automating the creation, management, and monitoring aspects of standby database environments. Oracle Data Guard automates the otherwise manual process of maintaining a transactional consistent copy of an Oracle database to recover from the loss of or damage to the production database.