1. Real Application Clusters Administration and Deployment Guide
  2. Administering Database Instances and Cluster Databases

3 Administering Database Instances and Cluster Databases

This chapter describes how to administer Oracle Real Application Clusters (Oracle RAC) databases and database instances.

Note:

A multitenant Container Database (CDB) is the only supported architecture in Oracle Database 21c and later releases.

See Also:

The Oracle Enterprise Manager Cloud Control online help for more information about Oracle Enterprise Manager Cloud Control.

Overview of Oracle RAC Database Administration

Oracle RAC database administration requires certain privileges and administrative tasks can vary depending on the deployment model.

The policy-managed database deployment option is desupported in Oracle Database 23ai.

Parent topic: Administering Database Instances and Cluster Databases

Required Privileges for Oracle RAC Database Administration

Use the SYSRAC administrative privilege to manage Oracle RAC databases.

To increase security and further separate administrative duties, Oracle RAC database administrators manage Oracle RAC databases with the SYSRAC administrative privilege.

The SYSRAC administrative privilege is the default mode of connecting to the database by the Oracle Clusterware agent on behalf of Oracle RAC utilities, such as SRVCTL.

Related Topics

Parent topic: Overview of Oracle RAC Database Administration

Oracle RAC Database Deployment Models

Starting with Oracle Database 21c, there is a single, merged management style for Oracle RAC databases.

Note:

The policy-managed database deployment option is desupported in Oracle Database 23ai.

Prior to Oracle Database 21c, Oracle RAC databases support two different management styles and deployment models: administrator-managed deployment and policy-managed deployment.

Administrator-managed deployment requires that you statically configure each database instance to run on a specific node in the cluster. This deployment also requires that you configure database services to run on specific instances that belong to a particular database using the preferred and available designation.

Policy-managed deployment is based on server pools. In this deployment, database services run within a server pool as singleton or uniform across all of the servers in the server pool. Databases are deployed in one or more server pools and the size of the server pools determine the number of database instances in the deployment.

Starting with Oracle Database 21c, the two management styles are merged into a single deployment model that combines the best features of each model. The administrator-managed database deployment style now has additional capabilities that were previously available only in policy-managed databases. These enhancements result in a new, converged deployment style. To use the merged database management style, you must have a Container Database (CDB) with at least one Pluggable Database (PDB).

You manage the merged database deployment model using the same commands and utilities (such as SRVCTL, Oracle DBCA, or Oracle Enterprise Manager) as before. All commands and utilities, except for the policy-management specific commands such as srvpool commands, maintain backward compatibility to support the management of Oracle databases prior to Oracle Database 21c.

The merged database management style simplifies management of dynamic systems. The clusters and databases can expand or shrink as requirements change. The Oracle home software must be installed on every node in the cluster.

Benefits of the merged management style

The PDBs in the cluster database are available on all nodes, or a subset of the nodes, based on the cardinality setting for the PDB. The cardinality of a PDB governs the number of nodes where a PDB can run at the same time. If you use a number for cardinality instead of ALL, then the instances in which the PDBs are opened depend on the resources available to each instance.

A database instance is started on every server in the cluster that hosts a PDB. If you are using Oracle Automatic Storage Management (Oracle ASM) with Oracle Managed Files for your database storage, then, when an instance starts and there is no redo thread available, Oracle RAC automatically enables one and creates the required redo log files and undo tablespace.

Clients can connect to a PDB using the same SCAN-based connect string irrespective of which servers the PDBs are running on at the time.

Parent topic: Overview of Oracle RAC Database Administration

Tools for Administering Oracle RAC

The tools most commonly used to managed Oracle Real Application Clusters (Oracle RAC) databases and instances are the SRVCTL utility, Oracle Enterprise Manager, and SQL*Plus.

In many cases, you use these tools the same way to manage Oracle RAC environments as you would use them manage noncluster Oracle databases:

Parent topic: Administering Database Instances and Cluster Databases

Administering Oracle RAC with SRVCTL

The Server Control Utility (SRVCTL) is a command-line interface that you can use to manage Oracle Databases in a centralized manner.

Oracle made centralized, SRVCTL-based database management available in Oracle Database 11g release 2 (11.2) for single-instance Oracle Databases, using Oracle ASM in the Oracle Grid Infrastructure, for both a noncluster environment and Oracle RAC databases, based on Oracle Grid Infrastructure for a cluster. This enables homogeneous management of all Oracle Database types using SRVCTL. You can use SRVCTL to start and stop the database and instances, and to delete or move instances and services. You can also use SRVCTL to add services and manage configuration information, in addition to other resources in the cluster.

When you use SRVCTL to perform configuration operations on your cluster, SRVCTL stores configuration data in the Oracle Cluster Registry (OCR) in a cluster or Oracle Local Registry (OLR) in Oracle Restart environments. SRVCTL performs other operations, such as starting and stopping instances, by configuring and managing Oracle Clusterware resources, which define agents that perform database startup and shutdown operations using Oracle Call Interface APIs.

Note:

If you require your database (or database instance) to start using certain environment variables, then use the srvctl setenv command to set those variables for the database profile that is maintained for the database using SRVCTL. You do not need to set the ORACLE_HOME and ORACLE_SID environment variables, because SRVCTL maintains and sets those parameters, automatically.

Related Topics

Parent topic: Tools for Administering Oracle RAC

Administering Oracle RAC with Oracle Enterprise Manager

Oracle Enterprise Manager provides a central point of control for the Oracle RAC environment, allowing you to perform administrative tasks simultaneously on multiple cluster databases.

Based on the Oracle Enterprise Manager Cloud Control (Grid Control in Oracle Enterprise Manager 11g) graphical user interface (GUI), you can manage both non-clustered and Oracle RAC environments.

In Oracle Enterprise Manager, Oracle RAC-specific administrative tasks generally focus on two levels: tasks that affect an entire cluster database and tasks that affect specific instances. For example, you can use Oracle Enterprise Manager to start, stop, and monitor databases, cluster database instances, and their listeners, and to schedule jobs or set up alert thresholds for metrics. Or you can perform instance-specific commands such as setting parameters or creating resource plans. You can also use Oracle Enterprise Manager to manage schemas, security, and cluster database storage features.

Related Topics

Parent topic: Tools for Administering Oracle RAC

Administering Oracle RAC with SQL*Plus

Unlike SRVCTL or Oracle Enterprise Manager, SQL*Plus is an instance-oriented management tool.

SQL*Plus commands operate on the current instance. The current instance can be either the local default instance on which you initiated your SQL*Plus session, or it can be a remote instance to which you connect with Oracle Net Services. For an Oracle RAC environment that runs multiple instances on one database at the same time, this implies that you need to consider the extent to which SQL*Plus can operate on this instance.

Note:

The policy-managed database deployment option is desupported in Oracle Database 23ai.

For example, when using Pluggable Databases (PDBs) you must consider that any alteration performed on the PDB using a SQL*Plus connection will, by default, only affect the current instance. To make changes affecting all instances that belong to the PDB, you must use the ALTER PLUGGABLE DATABASE command with instance=all. When using PDBs you must connect, using a dynamic database service (net_service_name), to an instance, as PDBs represent themselves as dynamic database services associated with one or more instances of an Oracle RAC database.

Because, by default, the SQL*Plus prompt does not identify the current instance, you should direct your commands to the correct instance. Starting a SQL*Plus session and connecting to the database without specifying an instance directs all SQL*Plus commands to the local instance. In this case, the default instance is also the current instance.

Since the SQL*Plus prompt does not identify the current instance by default, you should direct your commands to the correct instance. Starting a SQL*Plus session and connecting to the database without specifying an instance directs all SQL*Plus commands to the local instance. In this case, the default instance is also the current instance. To connect to a different instance in SQL*Plus, issue a new CONNECT command and specify a remote instance net service name, as shown in the following example, where password is the password: 

CONNECT user_name@net_service_name
Enter password: password

Connecting as SYSOPER or SYSRAC enables you to perform privileged operations, such as instance startup and shutdown. Multiple SQL*Plus sessions can connect to the same instance at the same time. SQL*Plus automatically disconnects you from the first instance whenever you connect to another one.

Note:

Use the SYSASM privilege instead of the SYSRAC privilege to connect to and administer an Oracle ASM instance. If you use the SYSRAC privilege to connect to an Oracle ASM instance, then Oracle Database writes warnings to the alert log files because commands that run using the SYSRAC privilege on an Oracle ASM instance are deprecated.

Related Topics

Parent topic: Tools for Administering Oracle RAC

How SQL*Plus Commands Affect Instances

You can use SQL*Plus to start and stop instances in the Oracle RAC database.

Most SQL statements affect the current instance. You do not need to run SQL*Plus commands as root on Linux and UNIX systems or as Administrator on Windows systems. You need only the proper database account with the privileges that you normally use for a noncluster Oracle database. Some examples of how SQL*Plus commands affect instances are:

  • ALTER SYSTEM CHECKPOINT LOCAL affects only the instance to which you are currently connected, rather than the default instance or all instances.

  • ALTER SYSTEM CHECKPOINT or ALTER SYSTEM CHECKPOINT GLOBAL affects all instances in the cluster database.

  • ALTER SYSTEM SWITCH LOGFILE affects only the current instance.

    • To force a global log switch, use the ALTER SYSTEM ARCHIVE LOG CURRENT statement.

    • The INSTANCE option of ALTER SYSTEM ARCHIVE LOG enables you to archive each online redo log file for a specific instance.

The following table describes how SQL*Plus commands affect instances.

Table 3-1 How SQL*Plus Commands Affect Instances

SQL*Plus Command Associated Instance
ARCHIVE LOG

Always affects the current instance.
CONNECT

Affects the default instance if no instance is specified in the CONNECT command.

HOST

Affects the node running the SQL*Plus session, regardless of the location of the current and default instances.

RECOVER

Does not affect any particular instance, but rather the database.
SHOW INSTANCE

Displays information about the current instance, which can be different from the default local instance if you have redirected your commands to a remote instance.
SHOW PARAMETER

and

SHOW SGA

Displays parameter and SGA information from the current instance.
STARTUP

and

SHUTDOWN

Always affects the current instance. These are privileged SQL*Plus commands.

Parent topic: Tools for Administering Oracle RAC

Starting and Stopping Instances and Oracle RAC Databases

You can start and stop instances with Oracle Enterprise Manager, SQL*Plus, or SRVCTL.

Both Oracle Enterprise Manager and SRVCTL provide options to start and stop all of the instances in an Oracle Real Application Clusters (Oracle RAC) database with a single step.

Using any tool, you can choose the startup state to which you want to start the database. The state of the database and database instance will determine what operations you can perform. You can perform certain operations only when the database is in the MOUNT (NOMOUNT) state. Performing other operations requires that the database be in the OPEN state.

Note:

Oracle does not support running more than one instance of the same database on the same node.

To start an Oracle RAC database instance on a node in the cluster, you must first start the Oracle Grid Infrastructure stack on the node. An Oracle RAC database instance will not start on a server on which the Oracle Grid Infrastructure stack is not running.

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Starting One or More Instances and Oracle RAC Databases Using SRVCTL

Use SRVCTL start Oracle RAC databases and instances.

Note:

This section assumes that you are using an SPFILE for your database.

Enter the following SRVCTL syntax from the command line, providing the required database name and instance name, or include multiple instance names to start multiple specific instances:

  • To start your entire cluster database, that is, all of the instances and its dependencies, enter the following SRVCTL command:

    $ srvctl start database -db db_unique_name [-startoption start_options]

    The following SRVCTL command, for example, mounts all of the non-running instances of an Oracle RAC database:

    $ srvctl start database -db orcl -startoption mount

  • To start specific instances of a database, enter a comma-delimited list of instance names:

    $ srvctl start instance -db db_unique_name -instance "instance_name_list"
  [-startoption start_options]

    You must enclose a comma-delimited list in double quotation marks ("").

  • To start an instance of a database on a specific node, use the following command with a single node name:

    $ srvctl start instance -db db_unique_name -node node_name
  [-startoption start_options]

    Note:

    The policy-managed database deployment option is desupported in Oracle Database 23ai.

    Policy-managed databases were deprecated in Oracle Database 21c, and admin-managed database deployment was enhanced with functions similar to policy managed databases. By converging the automation provided by policy-managed database with the consistency of an admin-managed database, Oracle seeks to simplify database management tasks for database administrators. This converged database deployment provides the best of both options, such as providing the options to rank and define the order of database startup, without requiring you to choose a specific style during deployment.

    Note that this command also starts all enabled and non-running services and PDBs that have AUTOMATIC management policy, and for which the database role matches one of the service's roles.

Related Topics

Parent topic: Starting and Stopping Instances and Oracle RAC Databases

Stopping One or More Instances and Oracle RAC Databases Using SRVCTL

Use SRVCTL to stop instances and Oracle RAC databases.

The procedure for shutting down Oracle RAC instances is identical to shutting down instances in noncluster Oracle databases, with the following exceptions:

  • In Oracle RAC, shutting down one instance does not interfere with the operation of other running instances.

  • To shut down an Oracle RAC database completely, shut down every instance that has the database open or mounted.

  • After a NORMAL or IMMEDIATE shutdown, instance recovery is not required. Recovery is required, however, after you issue the SHUTDOWN ABORT command or after an instance terminates unusually. An instance that is still running performs instance recovery for the instance that shut down. If no other instances are running, the next instance to open the database performs instance recovery for any instances needing it.

  • Using the SHUTDOWN TRANSACTIONAL command with the LOCAL option is useful to shut down a particular Oracle RAC database instance. Transactions on other instances do not block this operation. If you omit the LOCAL option, then this operation waits until transactions on all other instances that started before you ran the SHUTDOWN command either commit or rollback, which is a valid approach, if you intend to shut down all instances of an Oracle RAC database.

    Note:

    SHUTDOWN TRANSACTIONAL and SHUTDOWN TRANSACTIONAL LOCAL both perform the same action on a nonclustered database but the two commands are different on an Oracle RAC database.

Enter the following SRVCTL syntax from the command line, providing the required database name and instance name, or include multiple instance names to stop multiple specific instances:

  • To stop your entire cluster database, that is, all of the instances and its enabled services, enter the following SRVCTL command:

    $ srvctl stop database -db db_unique_name [-stopoption stop_options]

    Use the TRANSACTIONAL stop option with the srvctl stop database command and the TRANSACTIONAL LOCAL stop option with the srvctl stop instance command.

  • To stop all instances and their enabled services that are managed by Oracle Clusterware on one or more nodes, enter the following SRVCTL command:

    $ srvctl stop instance -node "node_list" [-stopoption stop_options]

  • To stop one or more instances, enter the following SRVCTL syntax from the command line:

    $ srvctl stop instance -db db_unique_name {-node "node_list" | -instance "inst_name_list"} 
   [-stopoption stop_options]

    You can enter either a comma-delimited list of instance names to stop several instances or you can enter a node name to stop one instance. In Windows you must enclose a comma-delimited list in double quotation marks ("").

    This command also stops the services related to the terminated instances on the nodes where the instances were running. As an example, the following command shuts down the two instances, orcl3 and orcl4, on the orcl database using the failover option for CRS to find another node to run the services from it and the immediate stop option: 

    $ srvctl stop instance -db orcl -instance "orcl3,orcl4" -failover -stopoption immediate

Related Topics

Parent topic: Starting and Stopping Instances and Oracle RAC Databases

Stopping All Databases and Instances Using CRSCTL

You can use the crsctl stop crs command on the node or the crsctl stop cluster -all command to stop all instances on a node or the entire cluster.

When you want to stop an entire node or cluster (for maintenance purposes, for example), you run either the crsctl stop crs command on the node or the crsctl stop cluster -all command, provided you have the required cluster privileges. These commands stop all database instances running on a server or in the cluster and ensure that their state is recovered after you restart the cluster. Using CRSCTL also enables Oracle Clusterware to relocate services and other resources that can run elsewhere.

Using either of these CRSCTL commands to stop all database instances on a server or in the cluster can lead to the database instances being stopped similar to shutdown abort, which requires an instance recovery on startup. If you use SRVCTL to stop the database instances manually before stopping the cluster, then you can prevent a shutdown abort, but this requires that you manually restart the database instances after restarting Oracle Clusterware.

Parent topic: Starting and Stopping Instances and Oracle RAC Databases

Starting and Stopping Individual Instances Using SQL*Plus

If you want to start or stop only one instance and you are connected to your local node, then you must first ensure that your current environment includes the SID for the local instance.

Note that any subsequent commands in your session, whether inside or outside a SQL*Plus session, are associated with that same SID.

Note:

This section assumes you are using an SPFILE.

To start or shutdown your local instance, initiate a SQL*Plus session and connect with the SYSRAC or SYSOPER privilege and then issue the required command. For example to start and mount an instance on your local node, run the following commands in your SQL*Plus session:

   CONNECT / AS SYSRAC
   STARTUP MOUNT

Note:

If you use Oracle ASM disk groups, then use the SYSASM privilege instead of the SYSRAC privilege to connect to and administer the Oracle ASM instances.

Oracle recommends that you do not use SQL*Plus to manage Oracle ASM instances in an Oracle RAC environment. Oracle Clusterware automatically manages Oracle ASM instances, as required. If manual intervention is necessary, then use respective SRVCTL commands.

You can start multiple instances from a single SQL*Plus session on one node using Oracle Net Services. Connect to each instance in turn by using a Net Services connection string, typically an instance-specific alias from your tnsnames.ora file.

For example, you can use a SQL*Plus session on a local node to perform a transactional shutdown for two instances on remote nodes by connecting to each in turn using the instance's individual alias name. Assume the alias name for the first instance is db1 and that the alias for the second instance is db2. Connect to the first instance and shut it down as follows: 

   CONNECT /@db1 AS SYSRAC
   SHUTDOWN TRANSACTIONAL

Note:

To ensure that you connect to the correct instance, you must use an alias in the connect string that is associated with only one instance. If you use a connect string that uses a TNS alias that connects to a service or an Oracle Net address that lists multiple IP addresses, then you might not be connected to the specific instance you want to shut down.

Then connect to and shutdown the second instance by entering the following from your SQL*Plus session:

   CONNECT /@db2 AS SYSRAC 
   SHUTDOWN TRANSACTIONAL

It is not possible to start or stop multiple instances, simultaneously, with SQL*Plus, so you cannot start or stop all of the instances for a cluster database with a single SQL*Plus command. You may want to create a script that connects to each instance in turn and start it up and shut it down. However, you must maintain this script manually if you add or drop instances.

Related Topics

Parent topic: Starting and Stopping Instances and Oracle RAC Databases

Starting and Stopping PDBs in Oracle RAC

You can use SRVCTL commands to manage PDBs.

Note:

Starting with Oracle Database 21c, installation of non-CDB Oracle Database architecture is no longer supported. The policy-managed database deployment option is desupported in Oracle Database 23ai.

Starting with Oracle Database 21c, PDBs are a resource managed by Oracle Clusterware. Consider a admin-managed CDB called raccont that has a PDB called spark.

Note:

If you attempt to create the service without first creating the PDB, then you will get an error message indicating you must create the PDB resource first.

If the spark PDB was created with cardinality set to 1, or 2, or ALL, then if you create a service named plug for the PDB, the service can use the –cardinality argument, too. If the spark PDB was created without specifying the -cardinality argument, then new services you create for the PDB use the -preferred or -available arguments, not the –cardinality argument.

Because PDBs are managed as an Oracle Clusterware resource, typical Oracle RAC-based management practices apply. For this reason, if the PDB spark has AUTOMATIC management policy, then the PDB is started when CDB starts. Similarly, if the PDB spark is in the online state when Oracle Clusterware is shut down on a server hosting this service and the management policy is set to MANUAL, then the PDB is restored to its original state after the restart of Oracle Clusterware on this server. The default PDB management policy is derived from the management policy of its CDB.

To start a Pluggable Database:
$ srvctl start pdb -db db_name -pdb pdb_name [-startoption start_options]
To start a Pluggable Database on specific nodes:
$ srvctl start pdb -db db_name -pdb pdb_name -node node_list 
   [-startoption start_options]

To stop a PDB and all its services on all nodes within a database using the IMMEDIATE option:

$ srvctl stop pdb -db db_name -pdb pdb_name -stopoption IMMEDIATE -drain_timeout 0
  -stopsvcoption IMMEDIATE
To stop a Pluggable Database on specific nodes:
$ srvctl stop pdb -db db_name -pdb pdb_name -node node_list
   [-stopoption stop_options] [-stopsvcoption stop_service_options 
   [-drain_timeout timeout]

If you do not want the spark PDB to restart when the Oracle RAC database is restarted on all, or on a specific node, use the following command: 

srvctl disable pdb -db raccont -pdb spark [-node node_name]

To view the status of the PDB service plug, use the following command: 

srvctl status service -db raccont -service plug -verbose

To view the status of the PDB spark, use the following command: 

srvctl status pdb -db raccont -pdb spark -detail

To modify the configuration of the PDB, use the following command:

srvctl modify pdb -db db_unique_name -pdb pdb_name 
     [-cardinality {num_of_instances | ALL}]
     [-maxcpu max_cpu_usage] [-mincpuunit min_cpu_usage] 
     [-rank rank] [-startoption start_options] 
     [-stopoption stop_options] [-policy policy]

Note:

You can modify the -cardinality parameter only if you had set the -cardinality parameter when creating the PDB.

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Local Rolling Database Maintenance

Starting with Oracle Database 23ai, you can patch Oracle Real Application Clusters (Oracle RAC) and Oracle RAC One Node databases locally in out-of-place mode without affecting availability and workload of the database.

Parent topic: Administering Database Instances and Cluster Databases

About Local Rolling Database Maintenance

Starting with Oracle Database 23ai, you can apply rolling patches and perform other maintenance operations locally for Oracle Real Application Clusters (Oracle RAC) and Oracle RAC One Node deployments.

Local rolling creates and starts a second database instance from the second home on the same node, instead of stopping the database instance and relocating the workload to another instance on another node. Local rolling database maintenance reduces the time to migrate the connections. This feature reduces brownout time by keeping the workload on the local node. You must ensure that there are enough CPU, memory, and other computing resources to temporarily run two instances.

Local rolling ensures that at least the same number of Oracle RAC and Oracle RAC One Node instances are running in the cluster during rolling migration of the database between two Oracle homes. Using this feature, you can do out-of-place rolling patching within a single cluster node.

When you use local rolling out-of-place patching, Oracle RAC creates a second instance in the new Oracle home, starts the second instance, and then stops the first instance in the old Oracle home on the node you are patching. This feature also preserves the PDB placement and the services, and thus the node keeps doing the same work it was doing before patching.

Note:

  • The srvctl modify database command automatically creates a new instance with a unique instance name (ORACL_SID).
  • The new instance name is the current instance name appended with an underscore (_) and a number. For example, if the current instance name is sales_1, then the new instance name could be sales_2. After the patching operation is complete, only the new instance runs on the patched node.
  • When you perform rolling patching the second time, the original ORACLE_SID is restored. For example, the ORACLE_SID goes back to sales_1 after the second rolling patching operation. The third rolling patching operation will use sales_2, and so on.

The local rolling out-of-place patching is optional in a multi-node environment. By default it is disabled. Use the -localrolling option with srvctl modify database to enable this feature.

Parent topic: Local Rolling Database Maintenance

Requirements for Using Local Rolling Maintenance

Learn what you need to do to configure and use local rolling database maintenance.

To take advantage of local rolling database maintenance capabilities in Oracle RAC, you must meet the following requirements:
  • Configure Oracle Managed Files (OMF).
  • Use the Server Parameters File (SPFILE).
  • Reset the THREAD and UNDO_TABLESPACE initialization parameters after local rolling is complete.
  • Do not run srvctl add instance, srvctl remove instance, or srvctl modify instance commands during local rolling patching.
  • You must ensure that enough free storage space is available to create a new redo thread and a new undo tablespace for each instance. This feature creates a new redo thread and a new undo tablespace for each new instance when you use this feature for the first time. The second and subsequent time you use this feature, the previously used old redo thread and undo tablespace are used, and new redo and undo are not created.

Parent topic: Local Rolling Database Maintenance

Patching Oracle RAC Database in Local Rolling Mode

You can patch Oracle Real Application Clusters (Oracle RAC) and Oracle RAC One Node databases in local rolling mode, reducing the time to migrate the connections.

  1. Download the Oracle Database installation image file (db_home.zip) and extract the image file into a new Oracle home directory.
    $ mkdir -p /u01/app/oracle/product/23.4.0/dbhome_1
$ chgrp oinstall /u01/app/oracle/product/23.4.0/dbhome_1
$ cd /u01/app/oracle/product/23.4.0/dbhome_1
$ unzip -q /tmp/db_home.zip
  2. From the new Oracle home directory, start the Oracle Database software installation and apply the required Release Updates (RUs).
    $ cd /u01/app/oracle/product/23.4.0/dbhome_1
$ ./runInstaller -applyRU patch_directory_location
  3. Prepare a new Oracle RAC or Oracle RAC One Node-enabled home.

    Note:

    You can also use Oracle FPP or any other method to install Oracle RAC software.
  4. Enable local rolling for your database.
    $ srvctl modify database –db mydb -oraclehome new_Oracle_home -localrolling
    This command also generates a name for the new instance.
  5. Transfer Oracle RAC and Oracle RAC One Node PDBs and services from the old Oracle home to the new Oracle home.
    $ srvctl transfer instance –d mydb [-node node_list] 
{[-stopoption stop_option] | -rollback} [-drain_timeout timeout] [-verbose]

    The new instance starts from the new Oracle home and waits for up to the time specified in the -drain_timeout parameter for the sessions to migrate to the new instance. The old instance stops when all the sessions are migrated to the new instance.

    Note:

    If -drain_timeout is not specified, then the maximum configured drain timeout of all the running services of the database on the specified nodes is used.
  6. Verify the database configuration changes.
    $ srvctl config database -db mydb
  7. Add or modify services and connect strings, as required.

Related Topics

Parent topic: Local Rolling Database Maintenance

Pluggable Database Rank

The PDB -rank parameter defines relative importance of the PDBs, which are created specifying cardinality, in a database with the RANK management policy.

The Pluggable Database (PDB) rank is a predefined value that you can assign to a PDB to specify workload importance of the PDB. Oracle Clusterware makes several decisions based on the rank of the PDB. By default, Oracle Clusterware has the same workload importance for each PDB. However, with the PDB -rank parameter, you can choose from a set of predefined values to distinguish workload importance of a PDB. The higher rank means the higher PDB workload importance, for example, the PDB rank 5 is the highest rank and 1 is the lowest rank.

The PDB -rank parameter is optional, and it is not set by default. You can configure it using the srvctl modify pdb command. When the -rank parameter is set, Oracle Clusterware gives precedence to the PDBs with ranks to perform the following operations:

  • Determines the startup order of the PDBs in the cluster. Oracle Clusterware attempts to start PDBs with the highest rank before the other PDBs with the lower ranks.

  • Shuts down a cluster database instance, with the RANK management policy, if there are no running PDBs that require that database instance.

  • Decides whether to refuse starting the PDBs or stop running the PDBs when the cluster does not have sufficient resources to meet resource requirements of the PDBs with higher ranks when PDB’s resource requirements are set to non-default values. The PDBs with non-default rank and resource requirement values have higher priority than the PDBs with default rank and resource requirement values.

    If a PDB in CDB1 has RANK 3 and a PDB in CDB2 has RANK 2, and if there are only enough resources to start only one CDB, then Oracle Clusterware starts CDB1 by dependency because the PDB in CDB1 has a higher rank. Oracle Clusterware does not start CDB2 because the PDB in CDB2 has a lower rank.

How PDB Rank Works?

If the PDB -rank parameter is defined, then Oracle Clusterware first considers PDB with the highest rank and then considers number of required CPUs while failing over the PDBs. For example, in a three node cluster with four CPUs in each node, and three PDBs named PDB1 with RANK 1 and CPU count 4, PDB2 with RANK 2 and CPU count 4, and PDB3 with RANK 3 and CPU count 4, Oracle Clusterware handles failover in the following order:

  1. The cluster has enough resources to start all PDBs. When the first node fails, PDB2 and PDB3 keep running, but Oracle Clusterware stops PDB1 because it has the lowest rank. If PDB2 and PDB3 were hosted on the failed node, then Oracle Clusterware stops PDB1 on the running nodes and starts PDB2 and PDB3 on these nodes.
  2. When the second node fails, PDB3 keeps running, but Oracle Clusterware stops PDB2 because it has the lowest rank. If PDB3 was hosted on the failed node, then Oracle Clusterware stops PDB2 on the running node and starts PDB3 on that node.
  3. PDBs can run from different CDBs. If you have multiple CDBs and any of these CDBs does not have a running PDB, then Oracle Clusterware shuts down the CDBs that do not have any running PDBs.

The rank of a PDB is set for the entire cluster, not only for the CDB in which you create a PDB.

Parent topic: Administering Database Instances and Cluster Databases

Pluggable Database Placement

Configure PDBs to either run explicitly in the specified CDB instances or run dynamically in any CDB or a subset of CDBs in the cluster.

You can choose from the following two placement options for the PDBs:

  • Preferred and Available PDBs: These PDBs can run only in the explicitly specified CDB instances that are running on the list of specified cluster nodes. While configuring such PDBs, you need to provide a CDB name and the list of instances or nodes where the CDB can run. You can modify the list of instances or nodes where the CDB can run.

  • Floating PDBs: These PDBs are created with specified cardinality and they can run on any instance of the CDB in which they are created. The cardinality of a PDB governs the number of nodes where a PDB can run at the same time. If you use a number for cardinality instead of ALL, then which instances the PDBs are opened in depends on the available resources of each instance.

    Oracle Clusterware evaluates resources for each cluster database instance based on the values of the -maxcpu and -mincpuunit parameters for the PDB. You must be logged in as either the grid or the root user to modify the -maxcpu, -mincpuunit, and -rank parameters.

You can configure the PDB placement option either while creating a new PDB or by modifying an existing PDB.

Parent topic: Administering Database Instances and Cluster Databases

Example of Creating a Pluggable Database with Cardinality and Rank

You can use these examples to see how to create an Oracle database and create a Pluggable Database, specifying cardinality, in the Oracle database.

You can define relative importance of Pluggable Databases in an Oracle database using the -rank parameter. This option works for the Pluggable Databases that are created specifying cardinality in a database with the RANK management policy.

The following examples show you how to create an Oracle database with the RANK management policy, add a Pluggable Database in the Oracle database specifying cardinality, and modify the PDB cardinality.

Example 3-1 Creating an Oracle Database Using SRVCTL

In this example, you create an Oracle database DATA with the RANK management policy using SRVCTL: 

$ srvctl add database -db db_unique_name -policy RANK -oraclehome $ORACLE_HOME -dbname DATA

Example 3-2 Creating a Pluggable Database Using SRVCTL

In this example, you create a Pluggable Database MYPDB, specifying cardinality, in Oracle database DATA using SRVCTL: 

$ srvctl add pdb -db DATA -pdb MYPDB -cardinality 2

Note:

If you set the management policy of your CDB to RANK, then the default policy of your PDBs that you create in that CDB will be set to RESTART.

Example 3-3 Checking PDB Configuration Using SRVCTL

In this example, you check configuration of Pluggable Database MYPDB using SRVCTL: 

$ srvctl config pdb -db DATA -pdb MYPDB
Pluggable database name: MYPDB
Application Root PDB: 
Cardinality: 2 
Maximum CPU count (whole CPUs): 0 
Minimum CPU count unit (1/100 CPU count): 0 
Start Option: open
Stop Option: immediate

Example 3-4 Modifying Pluggable Database Cardinality and Rank Using SRVCTL

In this example, as the grid user, you modify cardinality of Pluggable Database MYPDB, and set maximum CPU usage, minimum CPU usage, and rank using SRVCTL: 

$ srvctl modify pdb -db DATA -pdb MYPDB -cardinality 1 -maxcpu 3 -mincpuunit 20 -rank 2

Parent topic: Administering Database Instances and Cluster Databases

Reducing Downtime During Database and Instance Outages

Outages can be either planned (maintenance) or unplanned. You can use features to help minimize both types of outages.

In an Oracle RAC database, the outage of a single instance does not affect database availability. If a server or instance fails, restart and recovery are automatic, including the restarting of the subsystems, such as the listener and the Oracle Automatic Storage Management (Oracle ASM) processes, not only the database. User sessions that connect using a service can be transitioned to a remaining instance automatically. This happens transparently, with little impact to the users.

If the entire database needs to be stopped, then this can be done in a rolling fashion. You can stop each instance individually with stopping the entire database. While an instance is stopped, you perform the task that required the database to be stopped, and then restart the instance. This process is repeated until each instance in the Oracle RAC database has been stopped and restarted.

There are additional features you can use to minimize outages, both planned and unplanned:

  • The Oracle RAC high-availability framework maintains service availability by using Oracle Clusterware and resource profiles. Oracle Clusterware recovers and balances services according to business rules and the service attributes. If these services are used for client connections to the database, then they are automatically redirected to a remaining instance instead of getting an outage error.
  • For repairs, upgrades, and changes that require you to isolate one or more instances or nodes, Oracle RAC provides interfaces that relocate, disable, and enable services to minimize service disruption to application users.
  • Fast Application Notification (FAN) provides immediate interrupt of clients following outages related to the database, nodes, and networks. FAN notifies clients immediately when resources become available and initiates draining of database sessions so clients experience no outages during planned maintenance. Oracle connection pools, for example, use FAN to receive very fast notification of failures, to balance connections following failures, and to balance connections again after the failed components are repaired.
  • Application Continuity is a feature that enables the replay, in a non-disruptive and rapid manner, of a request against the database after a recoverable error that makes the database session unavailable so an outage appears to the user as no more than a delayed processing of the request.

For planned outages, you can achieve almost no interruption to users (zero brownout) in Oracle Database 21c and later releases. A phased shutdown of an instance allows the remaining instances to take ownership of locks and other resources so that after the instance is stopped, the amount of work required during reconfiguration is reduced. When the DBA issues a shutdown command for an instance, the instance is transitioned from an active instance to a passive instance.

A passive instance is in an ideal state to be stopped, which means as many resources and locks as possible are transitioned to the active instances. On a Oracle RAC cluster only one passive instance can exist at any time. When this process is initiated, the following actions take place:

  • The services running on the passive instance are stopped and relocated to another instance. This includes moving the connections from the passive instance to the active instance with a targeted drain timeout. The drain timeout indicates how long you want to wait for everything to complete, including the shutting down of the passive instance.
  • After the services have been drained from the passive instance, all Pluggable Databases (PDBs) are closed. All locks are transferred from the passive instance to active instances.
  • The instance is shutdown using the specified shutdown option.

Parent topic: Administering Database Instances and Cluster Databases

Oracle RAC High Availability Best Practices

Implement Oracle Real Application Clusters (Oracle RAC) best practices to achieve minimal downtime for patching and reconfiguration.

Parent topic: Administering Database Instances and Cluster Databases

Oracle RAC Two-Stage Rolling Updates

Starting with Oracle Database 23ai, Oracle RAC supports two-stage rolling patches that you can apply on one node at a time.

Oracle RAC two-stage rolling patches are new types of patches, which you can apply in a rolling fashion in stages. Once the patch is applied on the first node, the second node is patched, and so on. When all the nodes are patched, you can enable the patches. Fixes that you apply using this feature are disabled by default.

You can enable these fixes using the alter system enable RAC two_stage rolling updates all; command, after all the nodes are patched successfully. Use the V$RAC_TWO_STAGE_ROLLING_UPDATES view to list the patches applied using the Oracle RAC two-stage rolling updates.

Note:

Oracle RAC two-stage rolling updates apply to non-rolling RUs, but it does not apply to major Oracle RAC database upgrades.

Oracle RAC two-stage rolling updates reduce the need for downtime to apply non-rolling patches. However, not all non-rolling fixes can be applied in RAC rolling fashion. With this feature, the number of Oracle RAC non-rolling patches is significantly reduced.

Note:

Review the patch README file for instruction on how to apply the patch, and complete all the required steps before starting the patch upgrade.

This feature enables you to include all Oracle RAC bug fixes in RUs and new features. You are recommended to patch all the instances in a single maintenance window to avoid release version mismatch.

Parent topic: Oracle RAC High Availability Best Practices

Smooth Reconfiguration of Oracle RAC Instances

Smooth reconfiguration of Oracle Real Application Clusters (Oracle RAC) instances reduces brownout time during cluster reconfiguration.

The smooth reconfiguration feature reduces the brownout time caused by certain Oracle RAC operations such as nodes joining or leaving an Oracle RAC cluster, or when a node is undergoing maintenance or suffers a failure. This feature ensures continuous availability of Oracle RAC services and client applications.

The brownout time depends on the SGA size of the database. The bigger SGA size causes longer brownout. The brownout is related to redistribution of the resources for Global Enqueue Service (GES) and Cache Fusion to new instances when a new node joins or to redistribute resources to existing instances when a node fails or leaves the cluster. The Cache Fusion requests can trigger reconfiguration on an individual resource basis.

The smooth reconfiguration feature allows on-demand Cache Fusion reconfiguration for the Cache Fusion resources that client requests during cluster reconfiguration. The Cache Fusion request reconfigures immediately when the client requests so that the client can complete the request after the on-demand reconfiguration. The on-demand Cache Fusion reconfiguration can work in parallel with the ongoing cluster reconfiguration.

Parent topic: Oracle RAC High Availability Best Practices

Ordered Sequence Optimizations in Oracle RAC

Sequence is a database object from which multiple users may generate unique integers. You can use sequences to automatically generate primary key values.

Oracle Real Application Clusters (Oracle RAC) supports the following sequence configurations:
  • CACHE and ORDER: If your application requires sequence number ordering but can tolerate gaps, then use CACHE and ORDER to cache and order sequence numbers in Oracle RAC. Every instance caches the same set of numbers.
  • CACHE and NOORDER: If you use sequence numbers, then always use CACHE with the NOORDER option for optimal performance in sequence number generation. With the CACHE option, however, you may have gaps in the sequence numbers. This configuration has the least performance impact and it is the default configuration when creating a new sequence without options.
  • NOCACHE and ORDER: If your application requires ordered sequence numbers without gaps, then use NOCACHE and ORDER. The NOCACHE and ORDER combination has the most negative effect on performance compared to other caching and ordering combinations.
  • NOCACHE and NOORDER: If government regulations or laws legally require sequence numbers with limited gaps, then use NOCACHE and NOORDER. Ordering is not guaranteed in this configuration, however, it provides better performance than NOCACHE and ORDER.

Note:

Starting with Oracle Database 18c, you can use scalable sequences to provide better data load scalability instead of configuring a very large sequence cache. Scalable sequences improve the performance of concurrent data load operations, especially when the sequence values are used for populating primary key columns of tables.

In Oracle Database 23ai, ordered sequences in Oracle RAC environments are optimized for performance by reducing the number of lock acquisitions of the ordering enqueue. These improvements do not require any manual intervention or modification of the sequence. Ordered sequence optimization, along with the automatic sizing of the sequence cache feature that was introduced in Oracle Database 19c, works to improve performance of workloads that use ordered sequences.

Related Topics

Parent topic: Oracle RAC High Availability Best Practices

Verifying That Instances are Running

To verify that a database instance is available, use Oracle Enterprise Manager, SRVCTL, or SQL*Plus.

Parent topic: Administering Database Instances and Cluster Databases

Using SRVCTL to Verify That Instances are Running

You can use SRVCTL to verify that instances are running on a particular database.

The following command provides an example of using SRVCTL to check the status of the database instances for the Oracle RAC database named mail:

$ srvctl status database -db mail

This command returns output similar to the following:

Instance mail1 is running on node node11
Instance mail2 is running on node node10

Additionally, you can check whether a PDB is running in the cluster, as follows:

$ srvctl status pdb -db db_unique_name -pdb pdb_name

Parent topic: Verifying That Instances are Running

Using SQL*Plus to Verify That Instances are Running

You can use SQL*Plus to verify that database instances are running.

  1. On any node, from a SQL*Plus prompt, connect to a database instance by using a Net Services connection string, typically an instance-specific alias from your tnsnames.ora file. 

    CONNECT /@db1 as SYSRAC

  2. Query the V$ACTIVE_INSTANCES view, using the following statement:

    CONNECT SYS/as SYSRAC
Enter password: password
SELECT * FROM V$ACTIVE_INSTANCES;

    This query returns output similar to the following:

    INST_NUMBER INST_NAME    
-----------  ----------------- 
1            db1-sun:db1  
2            db2-sun:db2  
3            db3-sun:db3

The output columns for this example are shown in the following table.

Table 3-2 Descriptions of V$ACTIVE_INSTANCES Columns

Column Description
INST_NUMBER

Identifies the instance number.
INST_NAME

Identifies the host name and instance name as host_name:instance_name.

Related Topics

Parent topic: Verifying That Instances are Running

Terminating Sessions On a Specific Cluster Instance

You can use the ALTER SYSTEM KILL SESSION statement to terminate a session on a specific instance.

When a session is terminated, any session active transactions are rolled back, and resources held by the session (such as locks and memory areas) are immediately released and available to other sessions.

Using the ALTER SYSTEM KILL SESSION statement enables you to maintain strict application service-level agreements in Oracle RAC environments. Often, the goal of a service-level agreement is to carry out a transaction in a specified time limit. In an Oracle RAC environment, this may require terminating a transaction on an instance, and retrying the transaction on another instance within a specified time frame.

Note:

You can use Application Continuity to hide the cancellation of a transaction from the user, if the application initially used an Application Continuity-enabled dynamic database service to connect to the database instance.

To terminate sessions, follow these steps:

  1. Query the value of the INST_ID column in the GV$SESSION dynamic performance view to identify which session to terminate.

  2. Issue the ALTER SYSTEM KILL SESSION and specify the session index number (SID) and serial number of a session that you identified with the GV$SESSION dynamic performance view. 

    KILL SESSION 'integer1, integer2[, @integer3]'

    • For integer1, specify the value of the SID column.

    • For integer2, specify the value of the SERIAL# column.

    • For the optional integer3, specify the ID of the instance where the session to be terminated exists. You can find the instance ID by querying the GV$ tables.

    To use this statement, your instance must have the database open, and your session and the session to be terminated must be on the same instance unless you specify integer3.

If the session is performing some activity that must be completed, such as waiting for a reply from a remote database or rolling back a transaction, then Oracle Database waits for this activity to complete, marks the session as terminated, and then returns control to you. If the waiting lasts a minute, then Oracle Database marks the session to be terminated and returns control to you with a message that the session is marked to be terminated. The PMON background process then marks the session as terminated when the activity is complete.

Examples of Identifying and Terminating Sessions

The following examples provide three scenarios in which a user identifies and terminates a specific session. In each example, the SYSDBA first queries the GV$SESSION view for the SCOTT user's session to identify the session to terminate, and then runs the ALTER SYSTEM KILL SESSION statement to terminate the session on the instance.

Example 3-5 Identify and terminate the session on an busy instance

In this example, assume that the running session is SYSDBA on the instance INST_ID=1. The ORA-00031 message is returned because some activity must be completed before the session can be terminated. 

SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT';

       SID    SERIAL#    INST_ID
---------- ---------- ----------
        80          4          2

SQL> ALTER SYSTEM KILL SESSION '80, 4, @2';
alter system kill session '80, 4, @2'
*
ERROR at line 1:
ORA-00031: session marked for kill
SQL>

Example 3-6 Identify and terminate the session on an idle instance

In this example, assume that the running session is SYSDBA on the instance INST_ID=1. The session on instance INST_ID=2 is terminated immediately when Oracle Database runs the statement within 60 seconds. 

SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT';
 
       SID    SERIAL#    INST_ID
---------- ---------- ----------
        80          6          2
 
SQL> ALTER SYSTEM KILL SESSION '80, 6, @2';

System altered.

SQL>

Example 3-7 Using the IMMEDIATE parameter

The following example includes the optional IMMEDIATE clause to immediately terminate the session without waiting for outstanding activity to complete. 

SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT';
 
       SID    SERIAL#    INST_ID
---------- ---------- ----------
        80          8          2
 
SQL> ALTER SYSTEM KILL SESSION '80, 8, @2' IMMEDIATE;
 
System altered.
 
SQL>

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Overview of Initialization Parameter Files in Oracle RAC

The initialization parameters for an Oracle RAC database are stored in a SPFILE.

When you create the database, Oracle Database creates an SPFILE in the file location that you specify. This location can be either an Oracle Automatic Storage Management (Oracle ASM) disk group or a cluster file system. If you manually create your database, then Oracle recommends that you create an SPFILE from an initialization parameter file (PFILE).

Note:

Oracle RAC uses a traditional PFILE only if an SPFILE does not exist or if you specify PFILE in your STARTUP command. Oracle recommends that you use an SPFILE to simplify administration, to maintain parameter setting consistency, and to guarantee parameter setting persistence across database shutdown and startup events. In addition, you can configure Oracle Recovery Manager (RMAN) to back up your SPFILE.

All instances in the cluster database use the same SPFILE at startup. Because the SPFILE is a binary file, do not directly edit the SPFILE with an editor. Instead, change SPFILE parameter settings using Oracle Enterprise Manager or ALTER SYSTEM SQL statements.

Parent topic: Administering Database Instances and Cluster Databases

About Creating an SPFILE for Oracle RAC

All instances in an Oracle Real Application Clusters environment must use the same server parameter file.

However, when otherwise permitted, individual instances can have different settings of the same parameter within this one file. Instance-specific parameter definitions are specified as SID.parameter = value, where SID is the instance identifier.

For Oracle RAC, the location of the SPFILE is an attribute of the database resource managed by Oracle Clusterware. When creating a new SPFILE, if the instance from which you issued the command is running, then the following command creates a new SPFILE and automatically updates the database resource with the new SPFILE location:

CREATE SPFILE='location' FROM PFILE;

In this case, you can start up the database without referring to the server parameter file by name.

If the instance from which you issued the command is not running, then the SPFILE in the database resource must be updated manually using srvctl modify database -db dbname -spfile spfile_path. Also, if you use the following commands, then the SPFILE location is not automatically updated in the database resource: 

CREATE SPFILE FROM PFILE [AS COPY];
CREATE SPFILE='location' FROM PFILE AS COPY;
CREATE SPFILE FROM MEMORY;

When creating an SPFILE, if you include the FROM MEMORY clause (for example, CREATE PFILE FROM MEMORY or CREATE SPFILE FROM MEMORY), then the CREATE statement creates a PFILE or SPFILE using the current system-wide parameter settings. Because the FROM MEMORY clause requires all other instances to send their parameter settings to the instance that is trying to create the parameter file, the total processing time depends on the number of instances, the number of parameter settings on each instance, and the amount of data for these settings.

Parent topic: Overview of Initialization Parameter Files in Oracle RAC

Setting SPFILE Parameter Values for Oracle RAC

You can change SPFILE settings with Oracle Enterprise Manager or by using the SET clause of the ALTER SYSTEM statement.

Note:

Modifying the SPFILE using tools other than Oracle Enterprise Manager or SQL*Plus can corrupt the file and prevent database startup. To repair the file, you might be required to create a PFILE and then regenerate the SPFILE.

The examples in this section appear in ASCII text although the SPFILE is a binary file. Assume that you start an instance with an SPFILE containing the following entries:

*.OPEN_CURSORS=500
prod1.OPEN_CURSORS=1000

The value before the period (.) in an SPFILE entry identifies the instance to which the particular parameter value belongs. When an asterisk (*) precedes the period, the value is applied to all instances that do not have a subsequent, individual value listed in the SPFILE.

For the instance with the Oracle system identifier (SID) prod1, the OPEN_CURSORS parameter is set to 1000 even though it has a database-wide setting of 500. Parameter file entries that have the asterisk (*) wildcard character only affect the instances without an instance-specific entry. This gives you control over parameter settings for instance prod1. These two types of settings can appear in any order in the parameter file.

If another DBA runs the following statement, then Oracle Database updates the setting on all instances except the instance with SID prod1: 

ALTER SYSTEM SET OPEN_CURSORS=1500 sid='*' SCOPE=SPFILE;

The SPFILE now has the following entries for OPEN_CURSORS: 

*.OPEN_CURSORS=1500
prod1.OPEN_CURSORS=1000

Run the following statement to reset OPEN_CURSORS to its default value for all instances except prod1: 

ALTER SYSTEM RESET OPEN_CURSORS SCOPE=SPFILE;

The SPFILE now has only the following entry for prod1: 

prod1.OPEN_CURSORS=1000

Run the following statement to reset the OPEN_CURSORS parameter to its default value for instance prod1 only: 

ALTER SYSTEM RESET OPEN_CURSORS SCOPE=SPFILE SID='prod1';

Parent topic: Overview of Initialization Parameter Files in Oracle RAC

Parameter File Search Order in Oracle RAC

Oracle Database searches for your parameter file in a particular order depending on your platform. For Oracle RAC databases, you can easily determine the location of the parameter file by using the srvctl config database command.

On Linux and UNIX platforms, the search order is as follows:

  1. The location specified by the -spfile attribute for the database resource managed by Oracle Clusterware.

  2. The spfilesid.ora file in the location returned by the $ORACLE_HOME/bin/orabaseconfig utility, in the subdirectory /dbs.

  3. The spfile.ora file in the location returned by the $ORACLE_HOME/bin/orabaseconfig utility, in the subdirectory /dbs.

  4. The initsid.ora file in the location returned by the $ORACLE_HOME/bin/orabaseconfig utility, in the subdirectory /dbs.

On Windows platforms, the search order is as follows:

  1. %ORACLE_HOME%\database\spfilesid.ora

  2. %ORACLE_HOME%\database\spfile.ora

  3. %ORACLE_HOME%\database\initsid.ora

Note:

Oracle recommends that you do not use the default SPFILE names because all instances must use the same file and they all have different SIDs. Instead, store the SPFILE on Oracle ASM. If you store the SPFILE on a cluster file system, then use the following naming convention for the SPFILE: path/dbs/spfiledb_unique_name.ora. Create a PFILE named path/dbs/initsid.ora that contains the name SPFILE=path/dbs/spfiledb_unique_name.ora.

Related Topics

Parent topic: Overview of Initialization Parameter Files in Oracle RAC

Backing Up the Server Parameter File

Oracle recommends that you regularly back up the server parameter file for recovery purposes.

Do this using Oracle Enterprise Manager or use the CREATE PFILE statement. For example: 

CREATE PFILE='/u01/oracle/dbs/test_init.ora'
FROM SPFILE='/u01/oracle/dbs/test_spfile.ora';

You can use Recovery Manager (RMAN) to create backups of the server parameter file. You can also recover an SPFILE by starting an instance using a client-side initialization parameter file. Then re-create the server parameter file using the CREATE SPFILE statement. Note that if the parameter file that you use for this operation was for a single instance, then the parameter file does not contain instance-specific values, even those that must be unique in Oracle RAC instances. Therefore, ensure that your parameter file contains the appropriate settings as described earlier in this chapter.

To ensure that your SPFILE (and control files) are automatically backed up by RMAN during typical backup operations, use Oracle Enterprise Manager or the RMAN CONTROLFILE AUTOBACKUP statement to enable the RMAN autobackup feature

Related Topics

Parent topic: Overview of Initialization Parameter Files in Oracle RAC

Initialization Parameter Use in Oracle RAC

By default, most parameters are set to a default value and this value is the same across all instances.

However, many initialization parameters can also have different values on different instances as described in Initialization Parameters Specific to Oracle RAC. Other parameters must either be unique or identical as described in the following sections:

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Initialization Parameters Specific to Oracle RAC

The following table summarizes the initialization parameters used specifically for Oracle RAC databases.

Parameter Description
ACTIVE_INSTANCE_COUNT

This initialization parameter was deprecated in Oracle RAC 11g release 2 (11.2). Instead, use a service with one preferred and one available instance.
ASM_PREFERRED_READ_FAILURE_GROUPS

Specifies a set of disks to be the preferred disks from which to read mirror data copies. The values you set for this parameter are instance specific and need not be the same on all instances.
CLUSTER_DATABASE

Enables a database to be started in cluster mode. Set this parameter to TRUE.

CLUSTER_DATABASE_INSTANCES

Oracle RAC uses this parameter to allocate adequate memory resources. It must be set to the same value on all instances.

Note:The policy-managed database deployment option is desupported in Oracle Database 23ai.

You can set this parameter to a value that is greater than the current number of instances, if you are planning to add instances.

CLUSTER_INTERCONNECTS

Specifies an alternative cluster interconnect for the private network when there are multiple interconnects.

Notes:

  • Oracle recommends that all Oracle databases and Oracle Clusterware use the same interconnect network.

  • Oracle does not recommend setting the CLUSTER_INTERCONNECTS parameter except in certain situations.

  • This parameter is stored in the Grid Plug and Play profile in a Grid Plug and Play environment.
DB_NAME

If you set a value for DB_NAME in instance-specific parameter files, the setting must be identical for all instances.

DISPATCHERS

Set the DISPATCHERS parameter to enable a shared server configuration, that is a server that is configured to enable many user processes to share very few server processes. With shared server configurations, many user processes connect to a dispatcher. The DISPATCHERS parameter may contain many attributes.

Oracle recommends that you configure at least the PROTOCOL and LISTENER attributes. PROTOCOL specifies the network protocol for which the dispatcher process generates a listening end point. LISTENER specifies an alias name for the Oracle Net Services listeners. Set the alias to a name that is resolved through a naming method such as a tnsnames.ora file. The tnsnames.ora file contains net service names. Clients, nodes, and the Oracle Performance Manager node need this file. Oracle Enterprise Manager Cloud Control does not require tnsnames.ora entries on the client.

GCS_SERVER_PROCESSES

This static parameter specifies the initial number of server processes for an Oracle RAC instance's Global Cache Service (GCS). The GCS processes manage the routing of inter-instance traffic among Oracle RAC instances. The default number of GCS server processes is calculated based on system resources with a minimum setting of 2. For systems with one CPU, there is one GCS server process. For systems with two to eight CPUs, there are two GCS server processes. For systems with more than eight CPUs, the number of GCS server processes equals the number of CPUs divided by 4, dropping any fractions. For example, if you have 10 CPUs, then 10 divided by 4 means that your system has 2 GCS processes. You can set this parameter to different values on different instances.

INSTANCE_NAME

Specifies the unique name of an instance. Clients can use this name to force their session to be connected to a specific instance in the cluster. The format of the INSTANCE_NAME parameter is generally db_unique_name_instance_number, such as orcldb_2.

Note: In Grid Plug and Play environments, the INSTANCE_NAME parameter is not required and defaults to db_unique_name_instance_number if not specified.

RESULT_CACHE_MAX_SIZE

In a clustered database, you can either set RESULT_CACHE_MAX_SIZE=0 on every instance to disable the result cache, or use a nonzero value on every instance to enable the result cache. To switch between enabled and disabled result cache requires that you restart every instance:

  • Enabling the result cache: Set RESULT_CACHE_MAX_SIZE to a value greater than 0, or leave the parameter unset. You can size the cache differently on individual instances.

  • Disabling the result cache: Set RESULT_CACHE_MAX_SIZE=0 on all instances to disable the result cache. If you set RESULT_CACHE_MAX_SIZE=0 upon start up of any one instance, then you must set the parameter to zero on all instance start ups because disabling the result cache must done cluster-wide. Disabling the result cache on some instances may lead to incorrect results.

If you do not set the RESULT_CACHE_MAX_SIZE parameter, the parameter resolves to a default, nonzero value.

Starting with Oracle Database 21c, the result cache fetch functionality has been enhanced. Before fetching a cached result from a remote instance, the database uses heuristics to determine if it is more cost efficient to recompute the result on the local instance. You can monitor the use of this functionality by querying the V$RESULT_CACHE_OBJECTS and V$RESULT_CACHE_STATISTICS views.

SERVICE_NAMES

When you use services, Oracle recommends that you do not set a value for the SERVICE_NAMES parameter but instead you should create cluster managed services through the Cluster Managed Services page in Oracle Enterprise Manager Cloud Control. This is because Oracle Clusterware controls the setting for this parameter for the services that you create and for the default database service.

The service features described in Workload Management with Dynamic Database Services are not directly related to the features that Oracle provides when you set SERVICE_NAMES. In addition, setting a value for this parameter may override some benefits of using services.

Note: Oracle recommends that client connections use services rather than instance names. Entries in the SERVICE_NAMES parameter may be used by client connections rather than the INSTANCE_NAME parameter value. The SERVICE_NAMES parameter may include one or more names and different instances may share one or more names with other instances, enabling a client to connect to either a specific instance or to any one of a set of instances, depending on the service name chosen in the connection string.

SPFILE

When you use an SPFILE, all Oracle RAC database instances must use the SPFILE and the file must be on shared storage.
THREAD

Specifies the number of the redo threads to be used by an instance. You can specify any available redo thread number if that thread number is enabled and is not used. If specified, this parameter must have unique values on all instances. The best practice is to use the INSTANCE_NAME parameter to specify redo log groups.

Related Topics

Parent topic: Initialization Parameter Use in Oracle RAC

Parameters That Must Have Identical Settings on All Instances

Certain parameters that are critical at database creation or that affect certain database operations must have the same value for every instance in an Oracle RAC database.

Specify these initialization parameter values in the SPFILE or in the individual PFILEs for each instance. The following list contains the parameters that must be identical on every instance:

The following parameters must be identical on every instance only if the parameter value is set to zero:

  • DML_LOCKS
  • RESULT_CACHE_MAX_SIZE

Parent topic: Initialization Parameter Use in Oracle RAC

Parameters That Should Have Identical Settings on All Instances

Oracle recommends that the parameters listed here have identical settings on all instances.

Oracle recommends that you set the values for the parameters in Table 3-3 to the same value on all instances. Although you can have different settings for these parameters on different instances, setting each parameter to the same value on all instances simplifies administration.

Table 3-3 Parameters That Should Have Identical Settings on All Instances

Parameter Description
ARCHIVE_LAG_TARGET

Different values for instances in your Oracle RAC database are likely to increase overhead because of additional automatic synchronization performed by the database processing.

When using either Oracle GoldenGate downstream capture or Oracle GoldenGate integrated capture mode in a downstream capture configuration with your Oracle RAC database, the value must be greater than zero.
CLUSTER_DATABASE_INSTANCES

While it is preferable for this parameter to have identical settings across all Oracle RAC database instances, it is not required.
LICENSE_MAX_USERS

Because this parameter determines a database-wide limit on the number of users defined in the database, it is useful to have the same value on all instances of your database so you can see the current value no matter which instance you are using. Setting different values may cause Oracle Database to generate additional warning messages during instance startup, or cause commands related to database user management to fail on some instances.
LOG_ARCHIVE_FORMAT

If you do not use the same value for all your instances, then you unnecessarily complicate media recovery. The recovering instance expects the required archive log file names to have the format defined by its own value of LOG_ARCHIVE_FORMAT, regardless of which instance created the archive log files.

Databases that support Oracle Data Guard, either to send or receive archived redo log files, must use the same value of LOG_ARCHIVE_FORMAT for all instances.

SPFILE

If this parameter does not identify the same file to all instances, then each instance may behave differently and unpredictably in fail over, load-balancing, and during normal operations. Additionally, a change you make to the SPFILE with an ALTER SYSTEM SET or ALTER SYSTEM RESET command is saved only in the SPFILE used by the instance where you run the command. Your change is not reflected in instances using different SPFILEs.

If the SPFILE values are different in instances for which the values were set by the server, then you should restart the instances that are not using the default SPFILE.
TRACE_ENABLED

If you want diagnostic trace information to be always available for your Oracle RAC database, you must set TRACE_ENABLED to TRUE on all of your database instances. If you trace on only some of your instances, then diagnostic information might not be available when required should the only accessible instances be those with TRACE_ENABLED set to FALSE.

UNDO_RETENTION

By setting different values for UNDO_RETENTION in each instance, you are likely to reduce scalability and encounter unpredictable behavior following a failover. Therefore, you should carefully consider whether there are any benefits before you assign different values for this parameter to the instances in your Oracle RAC database.

Parent topic: Initialization Parameter Use in Oracle RAC

Quiescing Oracle RAC Databases

The procedure for quiescing Oracle RAC databases is identical to quiescing a noncluster database.

You use the ALTER SYSTEM QUIESCE RESTRICTED statement from one instance. You cannot open the database from any instance while the database is in the process of being quiesced. When all non-DBA sessions become inactive, the ALTER SYSTEM QUIESCE RESTRICTED statement finishes, and the database is considered as in a quiesced state. In an Oracle RAC environment, this statement affects all instances, not only the one from which the statement is issued.

To successfully issue the ALTER SYSTEM QUIESCE RESTRICTED statement in an Oracle RAC environment, you must have the Database Resource Manager feature activated, and it must have been activated since instance startup for all instances in the cluster database. It is through the facilities of the Database Resource Manager that non-DBA sessions are prevented from becoming active. Also, while this statement is in effect, any attempt to change the current resource plan is queued until after the system is unquiesced.

These conditions apply to Oracle RAC:

  • If you issued the ALTER SYSTEM QUIESCE RESTRICTED statement but Oracle Database has not finished processing it, you cannot open the database.

  • You cannot open the database if it is in a quiesced state.

  • The ALTER SYSTEM QUIESCE RESTRICTED and ALTER SYSTEM UNQUIESCE statements affect all instances in an Oracle RAC environment, not only the instance that issues the command.

Note:

You cannot use the quiesced state to take a cold backup. This is because Oracle Database background processes may still perform updates for Oracle Database internal purposes even while the database is in quiesced state. In addition, the file headers of online data files continue to look like they are being accessed. They do not look the same as if a clean shutdown were done. You can still take online backups while the database is in a quiesced state.

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Administering Multiple Cluster Interconnects on Linux and UNIX Platforms

In Oracle RAC environments that run on Linux and UNIX platforms, you can use the CLUSTER_INTERCONNECTS initialization parameter to specify an alternative interconnect to the one Oracle Clusterware is using for the private network.

Note:

The CLUSTER_INTERCONNECTS initialization parameter should not be set to highly available IP (HAIP) addresses provided by Redundant Interconnect Usage. HAIP addresses are recognized automatically.

If you set multiple values for CLUSTER_INTERCONNECTS, then Oracle Database uses all of the network interfaces that you specify for the interconnect, providing load balancing if all of the listed interconnects remain operational. You must use identical values, including the order in which the interconnects are listed, on all instances of your database when defining multiple interconnects with this parameter.

Note:

Oracle does not recommend setting the CLUSTER_INTERCONNECTS initialization parameter, which overrides the default interconnect settings at the operating system level.

Instead, the best practice is to use Redundant Interconnect Usage, available with Oracle Grid Infrastructure for Oracle RAC and Oracle Real Application Clusters One Node databases, and later. Oracle Database uses operating system-based network bonding technologies to enable high availability (and load balancing) for network interface cards meant to be used as the cluster interconnect. If you want to use multiple database versions in one cluster, you can combine both techniques. Redundant Interconnect Usage will use the interfaces as presented on the operating system level, regardless of bonding. For more information regarding bonding technologies contact your operating system vendor.

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Use Cases for Setting the CLUSTER_INTERCONNECTS Parameter

The CLUSTER_INTERCONNECTS initialization parameter requires an IP address. It enables you to specify multiple IP addresses, separated by colons. Oracle RAC network traffic is distributed between the specified IP addresses.

Note:

Oracle recommends that all databases and Oracle Clusterware use the same interconnect network.

Typically, you set the CLUSTER_INTERCONNECTS parameter only in the following situations:

  • The cluster is running multiple databases and you need the interconnect traffic to be separated and you do not use Redundant Interconnect Usage.

  • You have a single IP address that is made highly available by the operating system, and it does not have a stable interface name (for example, the name can change when you restart).

Do not set the CLUSTER_INTERCONNECTS parameter for the following common configurations:

  • If you want to use Redundant Interconnect Usage.

  • If you have only one cluster interconnect.

  • If the default cluster interconnect meets the bandwidth requirements of your Oracle RAC database, which is typically the case.

Consider the following important points when specifying the CLUSTER_INTERCONNECTS initialization parameter:

  • The CLUSTER_INTERCONNECTS initialization parameter is useful only in Linux and UNIX environments where UDP IPC is enabled.

  • Specify a different value for each instance of the Oracle RAC database when setting the CLUSTER_INTERCONNECTS initialization parameter in the parameter file.

  • The IP addresses you specify for the different instances of the same database on different nodes must belong to network adapters that connect to the same interconnect network.

  • If you specify multiple IP addresses for this parameter, then list them in the same order for all instances of the same database. For example, if the parameter for the first instance on node1 lists the IP addresses of the alt0:, fta0:, and ics0: devices in that order, then the parameter for the second instance on node2 must list the IP addresses of the equivalent network adapters in the same order.

  • If an operating system error occurs while Oracle Database is writing to the interconnect that you specify with the CLUSTER_INTERCONNECTS parameter, then Oracle Database returns an error even if some other interfaces are available. This is because the communication protocols between Oracle Database and the interconnect can vary greatly depending on your platform. See your Oracle Database platform-specific documentation for more information.

Example

Consider setting CLUSTER_INTERCONNECTS when a single cluster interconnect cannot meet your bandwidth requirements. You may need to set this parameter in data warehouse environments with high interconnect bandwidth demands from one or more databases that cannot use Redundant Interconnect Usage.

For example, if you have two databases with high interconnect bandwidth requirements, then you can override the default interconnect provided by your operating system and nominate a different interconnect for each database using the following syntax in each server parameter file where ipn is an IP address in standard dot-decimal format, for example: 144.25.16.214: 

Database One: crm1.CLUSTER_INTERCONNECTS = ip1
Database Two: ext1.CLUSTER_INTERCONNECTS = ip2

If you have one database with high bandwidth demands, then you can nominate multiple interconnects using the following syntax: 

CLUSTER_INTERCONNECTS = ip1:ip2:...:ipn

Related Topics

Parent topic: Administering Multiple Cluster Interconnects on Linux and UNIX Platforms

Customizing How Oracle Clusterware Manages Oracle RAC Databases

Use these examples to minimize Oracle Clusterware control over Oracle RAC databases, which you may need to do during upgrades.

By default, Oracle Clusterware controls database restarts in Oracle RAC environments. In some cases, you may need to minimize the level of control that Oracle Clusterware has over your Oracle RAC database, for example, during database upgrades.

To prevent Oracle Clusterware from restarting your Oracle RAC database when you restart your system, or to avoid restarting failed instances more than once, configure a management policy to define the degree of control. There are three management policies:

  • AUTOMATIC: This is the default management policy. The database is automatically restored to its previous running condition (started or stopped) upon restart of the database host computer.
  • MANUAL: The database is never automatically restarted upon restart of the database host computer. A MANUAL setting does not prevent Oracle Restart from monitoring the database while it is running and restarting it if a failure occurs.
  • NORESTART: Similar to the MANUAL setting, the database is never automatically restarted upon restart of the database host computer. A NORESTART setting, however, never restarts the database even if a failure occurs.

Use SRVCTL commands to display and change the Oracle Clusterware management policies, as shown in the following examples:

Example 1: Display the Current Management Policy

Use the following command syntax to display the current management policy where db_unique_name is the name of the database for which you want to change management policies: 

srvctl config database -db db_unique_name -all

Example 2: Change the Current Management Policy to Another Management Policy

Use the following SRVCTL command syntax to change the current management policy to either AUTOMATIC, MANUAL, or NORESTART:

srvctl modify database -db db_unique_name -policy [AUTOMATIC | MANUAL | NORESTART]

This command syntax sets the resource attribute of the database resource.

Example 3: Specify a Management Policy for a New Database

When you add a new database using the srvctl add database command, you can use the -policy parameter to specify the management policy as either AUTOMATIC, MANUAL, or NORESTART, as shown in the following example where db_unique_name is the name of the database: 

srvctl add database -db db_unique_name -policy [AUTOMATIC | MANUAL | NORESTART]
   -oraclehome $ORACLE_HOME -dbname DATA

This command syntax places the new database under the control of Oracle Clusterware. If you do not provide a management policy option, then Oracle Database uses the default value of automatic. After you change the management policy, the Oracle Clusterware resource records the new value for the affected database.

Related Topics

Parent topic: Administering Database Instances and Cluster Databases

Advanced Oracle Enterprise Manager Administration

You can install, configure, and monitor an Oracle Real Application Clusters (Oracle RAC) database from a single location using Oracle Enterprise Manager Cloud Control.

This section provides advanced administration tasks that are not covered in Monitoring and Tuning Oracle RAC Databases.

Parent topic: Administering Database Instances and Cluster Databases

Using Oracle Enterprise Manager Cloud Control to Discover Nodes and Instances

Discovering Oracle RAC database and instance targets in Oracle Enterprise Manager enables monitoring and administration.

Oracle Enterprise Manager Cloud Control enables you to use the Oracle Enterprise Manager console interface to discover Oracle Real Application Clusters (Oracle RAC) database and instance targets.

If the Oracle Enterprise Manager Cloud Control agents are installed on a cluster that has an Oracle RAC database, then Oracle RAC database targets are discovered at install time. You can use the console interface to discover targets if a database is created after agents are installed or if a database is not automatically discovered at agent install time.

To discover nodes and instances, use Oracle Enterprise Manager Cloud Control as follows:

  1. Log in to Oracle Enterprise Manager and click the Targets tab.

  2. Click the Database tab to view all of the available targets. The column labeled Types shows the Oracle RAC databases using the entry Cluster Database.

  3. Add the database target by selecting the target name, then clicking Add. The Add Database Target: Specify Host page appears, which enables you to add databases, listeners, and Oracle Automatic Storage Management (Oracle ASM) as monitored targets.

  4. Click the flashlight icon to display the available host names, select a host, then click Continue. The Add Database: Specify Source page appears.

  5. Either request Oracle Enterprise Managerr to discover only noncluster databases and listeners, or to discover all cluster databases, noncluster databases, and listeners on the cluster, then click Continue.

  6. If this procedure did not discover your reconfigured cluster database and all of its instances, you can use the Targets Discovered on Cluster page to manually configure your cluster database and noncluster databases.

Parent topic: Advanced Oracle Enterprise Manager Administration

Other Oracle Enterprise Manager Capabilities

Oracle Enterprise Manager provides a variety of administrative capabilities.

  • The Oracle Grid Infrastructure/Oracle RAC Provisioning deployment procedure provisions Oracle RAC and Oracle Grid Infrastructure. This procedure also has a feature called Profiles, which enables you to record the inputs and subsequently use them for repeated deployments.

  • Dynamic prerequisites for the new procedures enable Oracle Enterprise Manager, when connected to My Oracle Support, to download the latest prerequisites and tools for Oracle RAC provisioning.

  • The existing One-Click Extend Cluster Database capability now supports Oracle RAC stack.

  • The existing Delete/Scale down Oracle Real Application Clusters capability is certified with Oracle RAC clusters.

  • The existing Oracle Database Provisioning procedure now supports provisioning of single instances of Oracle Database.

  • A new deployment procedure—Oracle Grid Infrastructure Provisioning for Standalone Servers—has been introduced to provision Oracle Grid Infrastructure for noncluster databases.

Parent topic: Advanced Oracle Enterprise Manager Administration

Administering Jobs and Alerts in Oracle RAC

You can use the Administration tab in Oracle Enterprise Manager for an Oracle RAC database.

The Cluster Database Home page shows all of the instances in the Oracle Real Application Clusters (Oracle RAC) database and provides an aggregate collection of several statistics specific to Oracle RAC that are collected by the Automatic Workload Repository (AWR) for server manageability.

You do not need to navigate to an instance-specific page to see these details. However, on the Cluster Database Home page, if an instance is down that should be operating, or if an instance has a high number of alerts, then you can drill down to the instance-specific page for each alert.

To perform specific administrative tasks as described in the remainder of this section, log in to the target Oracle RAC database, navigate to the Cluster Database Home page, and click the Administration tab.

Parent topic: Advanced Oracle Enterprise Manager Administration

Administering Jobs in Oracle RAC

You can administer Oracle Enterprise Manager jobs at both the database and instance levels.

For example, you can create a job at the cluster database level to run on any active instance of the target Oracle Real Application Clusters (Oracle RAC) database. Or you can create a job at the instance level to run on the specific instance for which you created it. If there is a failure, then recurring jobs can run on a remaining instance.

Because you can create jobs at the instance level, cluster level, or cluster database level, jobs can run on any available host in the cluster database. This applies to scheduled jobs as well. Oracle Enterprise Manager also displays job activity in several categories, including, Active, History, and Library.

Use the Jobs tab to submit operating system scripts and SQL scripts and to examine scheduled jobs. For example, to create a backup job for a specific Oracle RAC database:

  1. Click Targets and click the database for which you want to create the job.

  2. Log in to the target database.

  3. When Oracle Enterprise Manager displays the Database Home page, click Maintenance.

  4. Complete the Enterprise Manage Job Wizard pages to create the job.

Administering Alerts in Oracle RAC with Oracle Enterprise Manager

You can use Oracle Enterprise Manager to configure Oracle RAC environment alerts.

You can also configure special Oracle RAC database tests, such as global cache converts, consistent read requests, and so on.

Oracle Enterprise Manager distinguishes between database- and instance-level alerts in Oracle RAC environments. Alert thresholds for instance-level alerts, such as archive log alerts, can be set at the instance target level. This function enables you to receive alerts for the specific instance if performance exceeds your threshold. You can also configure alerts at the database level, such as setting alerts for tablespaces, to avoid receiving duplicate alerts at each instance.

Related Topics

See Also:

Oracle Technology Network for an example of configuring alerts in Oracle RAC, and Oracle Database PL/SQL Packages and Types Reference for information about using packages to configure thresholds

Parent topic: Administering Jobs and Alerts in Oracle RAC

Using Defined Suspensions in Oracle Enterprise Manager

You can define suspensions (which are time periods in which database monitoring is suspended so that maintenance operations do not skew monitoring data or generate needless alerts) for all managed targets of an Oracle Real Application Clusters (Oracle RAC) database.

Defining suspensions prevents alerts from occurring while performing maintenance. You can define suspensions for an entire cluster database or for specific cluster database instances.