Overview of Oracle databases

There are two main configurations of Oracle databases.

  • Single instance: In a single instance configuration, a one-to-one relationship exists between the database and the instance. A database instance is associated with only one database at a time; however, multiple instances can run concurrently on the same server with each accessing its own database. In a single instance environment, data files, control files, and redo logs are located on a local or a shared cluster disk.
  • Oracle Real Application Clusters (Oracle RAC): In a RAC database configuration, a one-to-many relationship exists between the database and instances. An Oracle RAC environment can have up to 100 nodes concurrently accessing one single database. All data files, control files, and redo logs in a RAC environment must reside on cluster-aware shared disks, so that all the cluster database instances can access these storage components.

Interaction with Automatic Storage Management

Oracle ASM is a volume manager and a file system for Oracle database files that supports single-instance Oracle Database and Oracle Real Application Clusters (Oracle RAC) configurations. Oracle ASM simplifies the administration of Oracle related files by allowing the administrator to reference disk groups rather than individual disks and files. The ASM functionality is controlled by an ASM instance.

When you create an Oracle cluster or database within BMC Database Automation (BDA), you have the option of enabling the use of ASM. If ASM is enabled during the cluster create process, then ASM is automatically created on nodes that are added to that cluster. When a node is removed, ASM is removed. When a cluster is removed, ASM is removed with that cluster. When ASM is enabled, it collects information needed to create an ASM instance.

As an alternative to ASM for storing data files and redo logs, BDA also supports all clustered file systems supported by Oracle.

Interaction with listeners

You can use BMC Database Automation to provision listeners while creating a new single instance Oracle database and while creating Oracle clusters. Every listener that is created is registered with all database instances running on the local node. A single listener can be used to allow access to all instances running on the local node. There is no requirement for more than one listener for each node, which is the easiest configuration to manage.

Oracle Restart

Oracle Restart is a feature of Oracle that runs from the Oracle grid infrastructure home. When you install an Oracle grid infrastructure home, you enable support for a single node Oracle Restart configuration. This configuration enables Oracle Restart to run periodic check operations to monitor the health of Restart-enabled components. If a check operation fails for a component, the component is shut down and restarted.

The following components are automatically restarted by Oracle Restart:

  • Database instance
  • Oracle Net listener
  • Oracle ASM instance
  • Oracle ASM disk groups

Oracle RAC and RAC One Node

Oracle RAC One Node, introduced in Oracle version 11.2.0.1 databases, is a single instance of an Oracle RAC database that runs on one node in a cluster. It differs from an Oracle RAC database in that a full RAC database operates as an Active-Active solution where all the nodes in the cluster are active and can accept connections as a single unit. RAC One Node, on the other hand, works as an Active-Passive solution where only one node can be active at a time, and the other nodes are available to accept the workload of the first node should it go down.

For a walkthrough of using RAC One Node in BDA, see Walkthrough-Setting-up-Oracle-RAC-One-Node.

Oracle Multitenant architecture

BDA supports a new multitenant architectural option from Oracle for 12c databases. Multitenant architecture enables Oracle databases to be split into two portions: the Oracle software and the user data. The Oracle metadata becomes part of a Container Database (CDB), which can shared among multiple Pluggable Databases (PDBs). Each of the original databases (non-CDBs) corresponds to one of the PDBs. A single copy of the Oracle software is associated with the CDB and shared by all of the PDBs.

This architecture saves a significant amount of disk space on the servers where the databases reside, since the Oracle software is now shared among many databases. It also reduces the load on the servers where the databases reside, since the databases now share a single set of processes that run Oracle.

To create a CDB (with the option of PDBs within it), see Creating-a-single-instance-Oracle-database-on-Linux-and-UNIX.

 

Tip: For faster searching, add an asterisk to the end of your partial query. Example: cert*