Adding and Deleting Oracle RAC from Nodes on Linux and Unix Systems

Extend an existing Oracle Real Application Clusters (Oracle RAC) home to other nodes and instances in the cluster, and delete Oracle RAC from nodes and instances in the cluster.

About Adding and Deleting Nodes

Adding and deleting nodes modifies an Oracle RAC cluster; use cloning procedures instead when creating multiple installations from an existing Oracle RAC home. Before making changes, back up the Oracle Cluster Registry with ocrconfig -showbackup, and use “target node” to mean the node receiving the RAC extension.

Adding Oracle RAC to Nodes with Oracle Grid Infrastructure Installed

Adding Oracle RAC to a node requires procedures based on whether the Oracle home is local, shared through Oracle ACFS, or shared through another file system. Local homes use addnode.sh, root.sh, manual network configuration, and PDB activation; ACFS homes require starting the file-system resources, attaching the home, running addnode.sh -noCopy, and executing root.sh; other shared homes require creating and mounting the home path, attaching it, updating the Oracle Inventory, and running root.sh. Afterward, add the database instance to the target node and back up the OCR.

Adding Administrator-Managed Oracle RAC Database Instances to Target Nodes

Administrator-managed RAC instances can be added with Oracle Enterprise Manager or Oracle DBCA, which creates and configures instances, high-availability components, Oracle Net settings, startup behavior, and services. Interactive DBCA guides users through selecting the database and adding an instance, followed by administrative privilege verification with CVU and service configuration; silent DBCA uses -addInstance with the target node, global database name, optional instance name, and SYSDBA credentials.

Deleting Oracle RAC from a Cluster Node

Removing RAC from a node requires deleting its database instance and Oracle RAC software before removing the node from the cluster; if no instance exists, proceed directly to RAC removal. Before deleting administrator-managed instances, relocate services, ensure they can run on remaining instances, and remove the target instance from all service preferred and available lists.

Deleting Instances from Oracle RAC Databases

Instances can be removed with SRVCTL or Oracle DBCA, but services must first be relocated or reconfigured so the target instance is not required. Interactive DBCA deletion should run from another node while the target instance is active, and must be followed by verification that the redo thread is disabled and the instance is absent from OCR. Silent DBCA uses -deleteInstance and removes listener registration, the database instance, Oracle Net configuration, and the instance’s Oracle Flexible Architecture directories.

Using Oracle DBCA in Interactive Mode to Delete Instances from Nodes

Interactive DBCA instance deletion starts on a node other than the one hosting the target instance, using Instance Management to select and remove the instance from the RAC database. DBCA removes the instance and its Oracle Net configuration; afterward, verify and disable the corresponding redo thread if necessary, confirm removal from OCR with SRVCTL, and repeat the process for additional nodes.

Using Oracle DBCA in Silent Mode to Delete Instances from Nodes

Silent DBCA removes an Oracle RAC instance with -deleteInstance, requiring the global database name and instance name, with optional node and SYSDBA credentials. The operation deregisters the instance from listeners, deletes it from the configured node, removes Oracle Net configuration, and deletes its Oracle Flexible Architecture directory structure.

Removing Oracle RAC

Before removing RAC software from a node, disable and stop any listeners in the RAC home. Deinstall a local, nonshared Oracle home with deinstall -local; do not use this command for a shared home because it would remove software needed by other nodes, and instead continue with the shared-home removal procedure.

Deleting Nodes from A Cluster

After removing the database instance and Oracle RAC software, remove the node from the cluster by running the appropriate scripts on the target node to remove Oracle Clusterware, then execute the required scripts on remaining nodes to update the cluster’s node list.