Administering Oracle RAC One Node

Learn how to administer Oracle Real Application Clusters One Node (Oracle RAC One Node).

Oracle Real Application Clusters One Node (Oracle RAC One Node) is a single instance of an Oracle Real Application Clusters (Oracle RAC) database that runs on one node in a cluster. This option adds to the flexibility that Oracle offers for database consolidation. You can consolidate many databases into one cluster with minimal overhead while also providing the high availability benefits of failover protection, online rolling patch application, and rolling upgrades for the operating system and Oracle Clusterware.

Creating an Oracle RAC One Node Database

Oracle RAC One Node databases can be created with Fleet Patching and Provisioning, DBCA, or manual scripts, and registered with Clusterware using SRVCTL if automatic registration does not occur. Use srvctl add database -dbtype RACONENODE, including -server and -instance for administrator-managed databases; policy-managed deployment is desupported in Oracle AI Database 26ai. Configure at least one dynamic database service, and optionally specify an instance prefix, which determines instance names during relocation and failover. Oracle recommends managing these databases with SRVCTL because operations such as online relocation require it.

Converting Databases

SRVCTL can convert a single-instance Oracle RAC database to Oracle RAC One Node or convert an Oracle RAC One Node database back to Oracle RAC. Before converting to RAC One Node, ensure the RAC database has only one instance, configure services to prefer the retained instance, and change any PRECONNECT TAF policies to BASIC or NONE; the database must use Oracle Managed Files or have at least two redo threads. To convert back, use srvctl convert database -db db_unique_name -dbtype RAC, complete or cancel any active relocation, and then add further instances with srvctl add instance; policy-managed deployment is desupported in Oracle AI Database 26ai.

Online Database Relocation

Online database relocation moves an Oracle RAC One Node database to another node while maintaining service availability by starting a second instance, migrating services and connections, waiting for connection migration, and then stopping the former instance. Use srvctl relocate database and configure the relocation timeout for the connection-migration interval. Before relocation, ensure required password files are available on candidate nodes, maintain both instance-specific password files when shared storage is not used, and on Windows add the database service user to the Clusterware wallet. This feature is available only for Oracle RAC One Node databases, not standard Oracle RAC databases.