Oracle Real Application Clusters
Oracle Real Application Clusters (RAC) • Oracle Real Application Clusters allows oracle database to run any packages or custom application, unchanged across a set of clustered servers. Oracle RAC provides high availability and the most flexible scalability.
• Oracle RAC extends oracle database to store, update and efficiently retrieve data using multiple database instances on different servers at the same time
• The data files that make up the database must be residing in a shared storage that is accessible by all the servers in the cluster.
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Oracle RAC System
Establishing Connection to RAC using JDBC
Connecting to an Oracle RAC system is similar to connecting to a single instance of an Oracle database. When connecting to a single Oracle database instance, we specify either the SID or ServiceName of the instance to which you want to connect in the connection string. For example, the following connection string establishes a connection to the database instance
"Host=server1; Port=1521; ServiceName=Accting1"
In a RAC environment, multiple Oracle instances share the same physical data. In addition to the SID or ServiceName for each Oracle instance in the Oracle RAC system, a ServiceName exists for the entire Oracle RAC system. When an application uses the Oracle RAC system's ServiceName, the Oracle RAC system appears to be a single Oracle instance to the application.
For example, the following connection string establishes a connection to an Oracle instance in the Oracle RAC system named Accounting:
"Host=server1; Port=1521; ServiceName=Accounting"
The specific instance that is connected to is determined by a number of factors, including which instances are available and the load on those instances. Typically, the application does not need to know which instance to which it is connected.
Oracle RAC systems provide two methods of failover to provide reliable access to data:
• Connection
• Oracle RAC extends oracle database to store, update and efficiently retrieve data using multiple database instances on different servers at the same time
• The data files that make up the database must be residing in a shared storage that is accessible by all the servers in the cluster.
[pic]
Oracle RAC System
Establishing Connection to RAC using JDBC
Connecting to an Oracle RAC system is similar to connecting to a single instance of an Oracle database. When connecting to a single Oracle database instance, we specify either the SID or ServiceName of the instance to which you want to connect in the connection string. For example, the following connection string establishes a connection to the database instance
"Host=server1; Port=1521; ServiceName=Accting1"
In a RAC environment, multiple Oracle instances share the same physical data. In addition to the SID or ServiceName for each Oracle instance in the Oracle RAC system, a ServiceName exists for the entire Oracle RAC system. When an application uses the Oracle RAC system's ServiceName, the Oracle RAC system appears to be a single Oracle instance to the application.
For example, the following connection string establishes a connection to an Oracle instance in the Oracle RAC system named Accounting:
"Host=server1; Port=1521; ServiceName=Accounting"
The specific instance that is connected to is determined by a number of factors, including which instances are available and the load on those instances. Typically, the application does not need to know which instance to which it is connected.
Oracle RAC systems provide two methods of failover to provide reliable access to data:
• Connection