|Oracle® Real Application Clusters Administration and Deployment Guide
11g Release 2 (11.2)
Part Number E16795-07
This chapter describes how to administer Oracle Real Application Clusters (Oracle RAC) database instances and Oracle RAC databases.
The topics in this chapter include:
See Also:The Oracle Enterprise Manager online help for more information about Oracle Enterprise Manager
The following sections introduce Oracle RAC administration using the three tools that you commonly use to manage Oracle RAC databases and instances: Oracle Enterprise Manager, SQL*Plus, and the SRVCTL utility. In many cases, you use these tools the same way to manage Oracle RAC environments as you would use them manage single-instance Oracle databases:
Prior to Oracle RAC 11g release 2 (11.2), DBAs had to hard-code parameters, such as database instance number and redo threads, to allocate specific Oracle RAC database instances to nodes within the cluster. If a node in the cluster does not start, then the database instance does not start. In Oracle RAC 11g release 2 (126.96.36.199), this method of managing your Oracle RAC database continues to be available. An Oracle RAC database managed in this manner is referred to as an administrator-managed database. Administrator-managed databases include pre-11g release 2 (11.2) Oracle databases and upgraded Oracle databases. You can manage these databases using the same commands or methods (such as DBCA or Oracle Enterprise Manager) you used with previous releases of Oracle Database. All commands and utilities maintain backward compatibility.
With Oracle RAC 11g release 2 (11.2), you define a database as a resource in Oracle Clusterware. The resource is automatically created when you create your database with DBCA or the resource can be manually created by adding your database with SRVCTL. This resource contains the Oracle home, the
spfile, one or more server pools, and one or more Oracle ASM disk groups required for the database. The database resource also has a weak start dependency on the VIP, which means that the resource tries to start the VIP for the node when the database instance starts. If the VIP does not start successfully, then the instance still starts. The database service resource depends on a running VIP.
When you review the database resource for an administrator-managed database, you see a server pool defined with the same name as the Oracle database. This server pool is part of a special Oracle-defined server pool called Generic. Oracle RAC manages the Generic server pool to support administrator-managed databases. When you add or remove an administrator-managed database using either SRVCTL or DBCA, Oracle RAC creates or removes the server pools that are members of Generic. You cannot use SRVCTL or CRSCTL commands to modify the Generic server pool.
See Also:Oracle Clusterware Administration and Deployment Guide for more information about defining resources, server pools, and resource dependencies
In Oracle RAC 11g release 2 (11.2), Oracle introduces policy-managed databases to move away from any hard coding of parameters, to help to replace nodes in a cluster, or expand the cluster as requirements change. Policy-managed databases must be 11g release 2 (11.2) and cannot coexist on the same servers as administrator-managed databases.
Note:You cannot run more than one instance of the same database on the same node.
A policy-managed database is defined by cardinality, which is the number of database instances you want running during normal operations. A policy-managed database runs in one or more database server pools that are created in the cluster by the cluster administrator, and it can run on different servers at different times. A database instance starts on all servers that are in the server pools defined for the database. If you are using Oracle Automatic Storage Management (Oracle ASM) with Oracle Managed Files (OMF) 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 policy-managed database using the same SCAN-based connect string no matter which servers they happen to be running on at the time.
Check the current configuration of all services and the database (if you make a mistake and need to recover, then you can know what the configuration looked like when you began), as follows:
srvctl config database -d db_unique_name srvctl config service -d db_unique_name
Create a server pool for the policy-managed database (you must be a cluster administrator to do this), as follows:
srvctl add serverpool -g server_pool -l 0 -u n
In the preceding command,
n is the number of servers you want in the server pool.
Note:This step does not necessarily place servers in the newly-created server pool. If there are no servers in the Free pool from which the new server pool can allocate servers, for example, then you may have to use the
srvctl relocate servercommand to relocate a server from another server pool.
Modify the database to be in the new server pool, as follows:
srvctl modify database -d db_unique_name -g server_pool
Check the status of the database to confirm that it is now policy managed by repeating the commands in step 1.
See Also:Appendix A, "Server Control Utility Reference" for more information about these commands
Configure Oracle Enterprise Manager to recognize the change you made in the previous procedure, as follows:
In order for Oracle Enterprise Manager Database Control to recognize the new database instances, you must change the instance name from
db_unique_name_# (notice the additional underscore (_) before the number sign (#) character).
orapwd file in the
dbs/database directory (or create a new
orapwd file by running the
By default, there is an
orapwd file with the instance name appended to it, such as
orapwdORCL1. You must change the name of the file to correspond to the instance name you changed in the previous step. For example, you must change
orapwdORCL_1 or create a new
emca to reconfigure Oracle Enterprise Manager Database Control, as follows:
emca -config dbcontrol db -cluster
Conversely, you cannot directly convert a policy-managed database to an administrator-managed database. Instead, you can remove the policy-managed configuration using the
srvctl remove database and
srvctl remove service commands, and then create a new administrator-managed database with the
srvctl add database command.
See Also:"SRVCTL Command Reference" for more information about these commands
Services for administrator-managed databases continue to be defined by the
AVAILABLE definitions. For policy-managed databases, a service is defined to a database server pool and can either be uniform (running on all instances in the server pool) or singleton (running on only one instance in the server pool).
See Also:"Service Deployment Options" for more information about managing services
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. It has both the Database Control and Grid Control graphical user interfaces (GUIs) for managing single-instance and Oracle RAC environments. Because there is one Oracle Enterprise Manager Agent on each node of an Oracle RAC database, for Database Control you can use any URL for that database to administer it with Oracle Enterprise Manager.
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 the Console to manage schemas, security, and cluster database storage features.
Oracle Database 2 Day + Real Application Clusters Guide for a task-oriented guide that explains how to use Oracle Enterprise Manager to perform routine Oracle RAC database administrative tasks
"Advanced Oracle Enterprise Manager Administration" for advanced administration tasks not covered in Oracle Database 2 Day + Real Application Clusters Guide
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.
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.
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
SYSDBA 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.
SYSASMprivilege instead of the
SYSDBAprivilege to connect to and administer an Oracle ASM instance. If you use the
SYSDBAprivilege to connect to an Oracle ASM instance, then Oracle Database writes warnings to the alert log files because commands that run using the
SYSDBAprivilege on an Oracle ASM instance are deprecated.
See the Oracle Automatic Storage Management Administrator's Guide for more information.
Oracle Database Net Services Administrator's Guide for the proper specification of
Oracle Database Administrator's Guide for information about connecting to the database using
To change the SQL*Plus prompt so that it includes the name of the current instance:
SET SQLPROMPT '_CONNECT_IDENTIFIER> '
This command replaces the "SQL" string in front of the greater than symbol (>) with the user variable
_CONNECT_IDENTIFIER that displays the current instance name for the duration of your current session.
To change the prompt for all sessions automatically, add an entry similar to the following entry in your
glogin.sql file, found in the SQL*Plus administrative directory:
SET SQLPROMPT '_CONNECT_IDENTIFIER> '
You may include any other required text or SQL*Plus user variable between the single quotes in the command.
Most SQL statements affect the current instance. You can use SQL*Plus to start and stop instances in the Oracle RAC database. 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 single-instance Oracle database. Some examples of how SQL*Plus commands affect instances are:
Table 3-1 describes how SQL*Plus commands affect instances.
Table 3-1 How SQL*Plus Commands Affect Instances
|SQL*Plus Command||Associated Instance|
Always affects the current instance.
Always affects the current instance. These are privileged SQL*Plus commands.
Note:if you currently set environment variables other than Oracle home and Oracle SID in your session or profile when accessing the Oracle database, then use the
srvctl setenvcommand to set them for SRVCTL.
The Server Control Utility (SRVCTL) is a command-line interface that you can use to manage an Oracle RAC database from a single point. 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). SRVCTL performs other operations, such as starting and stopping instances, by configuring and managing Oracle Clusterware resources, that define agents that perform database startup and shutdown operations using Oracle Call Interface APIs.
See Also:Appendix A, "Server Control Utility Reference" for more information about SRVCTL
You can start and stop instances with Oracle Enterprise Manager, SQL*Plus or SRVCTL as described in the following sections. Both Oracle Enterprise Manager and SRVCTL provide options to start and stop all of the instances in an Oracle RAC database with a single step.
You can only perform certain operations when the database is in a
MOUNT state. Performing other operations requires that the database be
OPEN. In addition, some operations require that only one instance be in the required state, while other operations require that all of the instances be in an identical state.
Note:Oracle does not support running more than one instance of the same database on the same node.
The procedures in the following sections assume that you are using a server parameter file (SPFILE):
Before you can start an Oracle RAC instance, your clusterware and any required operating system-specific processes must be running. For more information about these processes, see your operating system documentation.
The procedure for shutting down Oracle RAC instances is identical to shutting down instances in single-instance Oracle, with the exceptions described here. See the Oracle Database Administrator's Guide for more information about shutting down Oracle databases.
To shut down an Oracle RAC database completely, shut down every instance that has the database open or mounted.
IMMEDIATE shutdown, instance recovery is not required. Recovery is required, however, after you issue the
ABORT command or after an instance terminates abnormally. The 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.
TRANSACTIONAL command with the
LOCAL option is useful to shutdown an instance after all active transactions on the instance have either committed or rolled back. This is in addition to what this command does for
IMMEDIATE. 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 the shutdown was issued either commit or rollback.
See the Oracle Database 2 Day + Real Application Clusters Guide for step-by-step instructions to start or stop a cluster database instance or a cluster database.
If you want to start or stop just one instance and you are connected to your local node, you should 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.
To start or shutdown your local instance, initiate a SQL*Plus session and connect with the
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 SYSDBA STARTUP MOUNT
Note:If you use Oracle ASM disk groups, use the
SYSASMprivilege instead of the
SYSDBAprivilege to connect to and administer the Oracle ASM instances. See the Oracle Automatic Storage Management Administrator's Guide for more information.
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
Note:To ensure that you connect to the correct instance, you must use an alias in the connect string that is associated with just one instance. If you use an alias to a service or with multiple addresses, you may not be connected to your intended instance.
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:
Then connect to and shutdown the second instance by entering the following from your SQL*Plus session:
CONNECT /@db2 AS SYSDBA 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.
See Also:SQL*Plus User's Guide and Reference for information about other startup and shut down keywords, such as
IMMEDIATE, and so on
Note:This section assumes that you are using a SPFILE for your database.
To start administrator-managed databases, enter a comma-delimited list of instance names:
In Windows you must enclose a comma-delimited list in double quotation marks (
To start policy-managed databases, enter a single node name:
$ srvctl start instance -d db_unique_name -n node_name [-o start_options]
Note that this command also starts all enabled and non-running services that have
AUTOMATIC management policy, and for which the database role matches one of the service's roles.
To stop one or more instances, enter the following SRVCTL syntax from the command line:
$ srvctl stop instance -d db_unique_name [ -i "instance_name_list" | -n node_name ] [ -o 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,
orcl4, on the
orcl database using the
immediate stop option:
$ srvctl stop instance -d orcl -i "orcl3,orcl4" -o immediate
To start or stop your entire cluster database, that is, all of the instances and its enabled services, enter the following SRVCTL commands:
The following SRVCTL command, for example, mounts all of the non-running instances of an Oracle RAC database:
$ srvctl start database -d orcl -o mount
See Also:Appendix A, "Server Control Utility Reference" for information about SRVCTL options and information about other administrative tasks that you can perform with SRVCTL
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 Table 3-2.
You can use the
ALTER SYSTEM KILL SESSION statement to terminate a session on a specific instance. When a session is terminated, any active transactions of the session are rolled back, and resources held by the session (such as locks and memory areas) are immediately released and available to other sessions.
Using this statement enables you to maintain strict application service-level agreements in Oracle RAC environments. Often, the goal of a service-level agreement is to execute 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.
To terminate sessions, follow these steps:
Query the value of the
INST_ID column in the
GV$SESSION dynamic performance view to identify which session to terminate
KILL SESSION 'integer1, integer2[, @integer3]'
integer1, specify the value of the SID column.
integer2, specify the value of the SERIAL# column.
For the optional
integer3, specify the ID of the instance where the session to be killed exists. You can find the instance ID by querying the
To use this statement, your instance must have the database open, and your session and the session to be terminated must be on the same instance unless you specify
If the session is performing some activity that must be completed, such as waiting for a reply from a remote database or rolling back a transaction, then Oracle Database waits for this activity to complete, marks the session as terminated, and then returns control to you. If the waiting lasts a minute, then Oracle Database marks the session to be terminated and returns control to you with a message that the session is marked to be terminated. The PMON background process then marks the session as terminated when the activity is complete.
The following examples provide a three scenarios in which a user identifies and terminates a specific session.
In this example, assume that the executing session is
SYSDBA on the instance
SYSDBA first queries the
GV$SESSION view for the
SCOTT user's session to identify the session to terminate, and then issues the
ALTER SYSTEM KILL SESSION statement to terminate the session on the instance
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$SESSION WHERE USERNAME='SCOTT'; SID SERIAL# INST_ID ---------- ---------- ---------- 80 4 2 SQL> ALTER SYSTEM KILL SESSION '80, 4, @2'; alter system kill session '80, 4, @2' * ERROR at line 1: ORA-00031: session marked for kill SQL>
In this example, assume that the executing session is
SYSDBA on the instance
INST_ID=1. The session on instance
INST_ID=2 is terminated immediately when Oracle Database executes the statement within 60 seconds.
SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT'; SID SERIAL# INST_ID ---------- ---------- ---------- 80 6 2 SQL> ALTER SYSTEM KILL SESSION '80, 6, @2'; System altered. SQL>
The following example include 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>
See Also:Oracle Database Administrator's Guide for more information about terminating sessions
When you create the database, Oracle Database creates an SPFILE in the file location that you specify. This location can be an Oracle ASM disk group, a cluster file system, or a shared raw device. 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
STARTUPcommand. Oracle recommends that you use SPFILE file 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 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
SYSTEM SQL statements.
If you include the
FROM MEMORY clause (for example,
CREATE PFILE FROM MEMORY or
CREATE SPFILE FROM MEMORY), the
CREATE statement creates a PFILE or SPFILE using the current system-wide parameter settings. In an Oracle RAC environment, the created file contains the parameter settings from each instance. 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 execution time depends on the number of instances, the number of parameter settings on each instance, and the amount of data for these settings.
This section includes the following topics:
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:
Note:The value before the dot in an SPFILE entry identifies the instance to which the particular parameter value belongs. When an asterisk precedes the dot, 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)
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
ALTER SYSTEM SET OPEN_CURSORS=1500 sid='*' SCOPE=MEMORY;
Then if you run the following statement on another instance, the instance with sid
prod1 also assumes the new setting of
ALTER SYSTEM SET OPEN_CURSORS=2000 sid='*' SCOPE=MEMORY;
In the following example, the server parameter file contains these entries:
Issue the following statement to make Oracle Database disregard the first entry from the server parameter file:
ALTER SYSTEM RESET SCOPE=SPFILE;
Issue the following statement to reset a parameter to its default value for instance
ALTER SYSTEM RESET OPEN_CURSORS SCOPE=SPFILE SID='prod1';
Oracle Database searches for your parameter file in a particular order depending on your platform.
On Linux and UNIX platforms, the search order is as follows:
On Windows platforms, the search order is as follows:
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:
.ora. Create a PFILE named
.orathat contains the default name
Oracle recommends that you regularly back up the server parameter file for recovery purposes. Do this using Oracle Enterprise Manager (as described in the Oracle Database 2 Day + Real Application Clusters Guide) or use the
CREATE PFILE statement. For example:
CREATE PFILE='?/dbs/initdbname.ora' FROM SPFILE='/dev/vx/rdsk/oracle_dg/dbspfile'
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
See Also:Oracle Database 2 Day + Real Application Clusters Guide to perform backup jobs using Oracle Enterprise Manager, and the Oracle Database SQL Language Reference for more information about the
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 Table 3-3. Other parameters must either be unique or identical as described in the following sections
Table 3-3 summarizes the initialization parameters used specifically for Oracle RAC databases. See Oracle Database Reference for additional information about these and other initialization parameters.
Table 3-3 Initialization Parameters Specific to Oracle RAC
This initialization parameter is deprecated in Oracle RAC 11g release 2 (11.2). Instead, use a service with one preferred and one available instance.
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.
Enables a database to be started in cluster mode. Set this parameter to
Oracle RAC uses this parameter to allocate adequate memory resources. It must be set to the same value on all instances.
You can set this parameter to a value that is greater than the current number of instances, if you are planning to add instances. For policy-managed databases, you should set this parameter to a higher value only if you intend to run a database with more than 16 instances. In this case, set the parameter to the expected maximum number of instances on which this database will run.
Specifies an alternative cluster interconnect for the private network when there are multiple interconnects. The
If you set a value for
Oracle recommends that you configure at least the
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 interinstance 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.
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
Note: In Grid Plug and Play environments, the
In a clustered database, you can either set
If you do not set the
When you use services, Oracle recommends that you do not set a value for the
Note: Entries in the
Each instance maintains its own
When you use an SPFILE, all Oracle RAC database instances must use the SPFILE and the file must be on shared storage.
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
See Also: Oracle Database SQL Language Reference for more information about the
Certain initialization 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 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:
INSTANCE_TYPE(RDBMS or ASM)
The following parameters must be identical on every instance only if the parameter value is set to zero:
When it is necessary to set parameters that have unique settings on a policy-managed database, you can ensure that instances always use the same name on particular nodes by running the
srvctl modify instance -n
instance_name command for each server that can be assigned to the database's server pool. Then a unique value of the parameter can be specified for
instance_name that is used whenever the database runs on
If you use the
ROLLBACK_SEGMENTS parameters, then Oracle recommends setting unique values for it by using the
SID identifier in the SPFILE. However, you must set a unique value for
INSTANCE_NUMBER for each instance and you cannot use a default value.
CLUSTER_INTERCONNECTS initialization parameter to specify an alternative interconnect to the one Oracle Clusterware is using for the private network. Each instance of the Oracle RAC database gets a unique value when setting the
CLUSTER_INTERCONNECTS initialization parameter.
See Also:"Administering Multiple Cluster Interconnects on Linux and UNIX Platforms" for more information about the
Oracle Database uses the
INSTANCE_NUMBER parameter to distinguish among instances at startup. Oracle Database uses the
INSTANCE_NAME parameter to assign redo log groups to specific instances. To simplify administration, use the same number for both the
INSTANCE_NUMBER parameters. With Oracle Database 11.2 using Grid Plug and Play, the instance name parameter is no longer required. If you do not specify the instance name, then instance name defaults to
ORACLE_SID environment variable, which comprises the database name and the number of the
INSTANCE_NAME assigned to the instance. When you specify
UNDO_TABLESPACE with automatic undo management enabled, then set this parameter to a unique undo tablespace name for each instance.
ASM_PREFERRED_READ_FAILURE_GROUPS initialization parameter, you can specify a list of preferred read failure group names. The disks in those failure groups become the preferred read disks. Thus, every node can read from its local disks. This results in higher efficiency and performance and reduced network traffic. The setting for this parameter is instance-specific, and the values need not be the same on all instances.
Oracle recommends that you set the values for the parameters in Table 3-4 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 3-4 Parameters That Should Have Identical Settings on All Instances
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 Streams with your Oracle RAC database, the value should be greater than zero.
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.
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
Databases that support Data Guard, either to send or receive archived redo log files, must use the same value of
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
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.
If you want diagnostic trace information to be always available for your Oracle RAC database, you must set
By setting different values for
The procedure for quiescing Oracle RAC databases is identical to quiescing a single-instance 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 just 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.
ALTER SYSTEM QUIESCE RESTRICTED and
ALTER SYSTEM UNQUIESCE statements affect all instances in an Oracle RAC environment, not just 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.
In Oracle RAC environments that run on Linux and UNIX platforms where UDP IPC is enabled, you can use the
CLUSTER_INTERCONNECTS initialization parameter to specify an alternative interconnect to the one Oracle Clusterware is using for the private network.
Oracle does not recommend setting the
CLUSTER_INTERCONNECTS parameter, which overrides the default interconnect settings at the operating system level. Instead, the best practice is to use operating system bonding techniques (also referred to as NIC (network interface card) bonding). See your platform-specific Oracle RAC installation guide for information about setting up NIC bonding at the operating system level.
This section includes the following topics:
Oracle does not recommend setting the
CLUSTER_INTERCONNECTS parameter when using a policy-managed database.
If you must set the
CLUSTER_INTERCONNECTS parameter for a policy-managed database, then Oracle recommends that you use the
srvctl modify instance -n
instance_name command for all servers in the server pool.
Oracle recommends that all databases and Oracle Clusterware use the same interconnect network.
Due to operating system limitations, you cannot use NIC bonding to provide increased bandwidth using multiple network interfaces.
The cluster is running multiple databases and you need the interconnect traffic to be separated.
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 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:
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.
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.
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 instance 1 on node 1 lists the IP addresses of the
ics0: devices in that order, then the parameter for instance 2 on node 2 must list the IP addresses of the equivalent network adapters in the same order. See the examples in "Usage Examples for the CLUSTER_INTERCONNECTS Parameter" for more information about setting multiple interconnects with this parameter.
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.
See Also:Oracle Database Reference for more information about the
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 as described here.
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
n is an IP address in standard dot-decimal format, for example:
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
If you set multiple values for
CLUSTER_INTERCONNECTS as in the preceding example, then Oracle Database uses all of the interconnects that you specify, 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.
To use the network interface whose IP address is
188.8.131.52 for all GCS, GES, and IPQ IPC traffic, set the
CLUSTER_INTERCONNECTS parameter as follows:
netstat command to display the IP address of a device. This command provides a map between device names and IP addresses. For example, to determine the IP address of a device, run the following command as the
# /usr/sbin/ifconfig -a fta0: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX> inet 184.108.40.206 netmask fffffc00 broadcast 220.127.116.11 ipmtu 1500 lo0: flags=100c89<UP,LOOPBACK,NOARP,MULTICAST,SIMPLEX,NOCHECKSUM> inet 127.0.0.1 netmask ff000000 ipmtu 4096 ics0: flags=1100063<UP,BROADCAST,NOTRAILERS,RUNNING,NOCHECKSUM,CLUIF> inet 10.0.0.1 netmask ffffff00 broadcast 10.0.0.255 ipmtu 7000 sl0: flags=10<POINTOPOINT> tun0: flags=80<NOARP>
In the preceding example, the interface
fta0: has an IP address of
18.104.22.168 and the interface
ics0: has an IP address of
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.
Note:When using third-party clusterware, Oracle recommends that you allow Oracle Clusterware to manage the Oracle RAC instances. If you set the instance to manual and start it with third-party clusterware, do not use the third-party clusterware to monitor and restart database instances, Oracle Clusterware must do that.
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 policy to define the degree of control. There are two policies: AUTOMATIC, which is the default, and MANUAL. If the policy is set to AUTOMATIC, the database is automatically restored to its previous running condition (started or stopped) upon restart of the database host computer. If 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.
Use SRVCTL commands to display and change the Oracle Clusterware policies, as shown in the following examples:
For example, use the following command syntax to display the current policy where
db_unique_name is the name of the database for which you want to change policies:
srvctl config database -d db_unique_name -a
Use the following SRVCTL command syntax to change the current policy to another policy where
policy_name is the name of the new policy for the database (that was identified by
db_unique_name in Example1):
srvctl modify database -d db_unique_name -y management_policy
This command syntax sets the resource attribute of the database resource.
When you add a new database using the SRVCTL command, you can use the
-y option to specify the management policy, as shown in the following example where
db_unique_name is the name of the database and
management_policy is the name of the policy:
srvctl add database -d db_unique_name -y management_policy -o $ORACLE_HOME -d 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 policy, the Oracle Clusterware resource records the new value for the affected database.
See Also:Appendix A, "Server Control Utility Reference" for more information about SRVCTL commands
You can install, configure, and monitor an Oracle RAC database from a single location using either Oracle Enterprise Manager Database Control or Oracle Enterprise Manager Grid Control.
This section provides advanced administration tasks that are not covered in Oracle Database 2 Day + Real Application Clusters Guide or in "Overview of Monitoring and Tuning Oracle RAC Databases".
See Also:Oracle Database 2 Day + Real Application Clusters Guide for a task-oriented guide that explains how to use Oracle Enterprise Manager to perform routine Oracle RAC database administrative tasks
This section includes the following topics:
Discovering Oracle RAC database and instance targets in Oracle Enterprise Manager enables monitoring and administration from the console:
Database Control does not require discovery because DBCA performs any necessary configuration while creating the database.
Grid Control enables you to use the Oracle Enterprise Manager console interface to discover Oracle RAC database and instance targets.
If the Grid Control agents are installed on a cluster that has an Oracle RAC database, 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 Grid Control as follows:
Log in to Oracle Enterprise Manager and click the Targets tab.
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.
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 ASM as monitored targets.
Click the flashlight icon to display the available host names, select a host, then click Continue. The Add Database: Specify Source page appears.
Either request Oracle Enterprise Manager to discover only single-instance databases and listeners, or to discover all cluster databases, single-instance databases, and listeners on the cluster, then click Continue.
Oracle Enterprise Manager performs discovery to locate and display the cluster database and its associated instances. The Targets Discovered on Cluster page appears. If this procedure did not discover your reconfigured cluster database and all of its instances, you can use this page to manually configure your cluster databases and single-instance databases.
This section lists Oracle Enterprise Manager capabilities available with Oracle Enterprise Manager 11g release 2 (11.2).
A new deployment procedure—Oracle Grid Infrastructure/Oracle RAC Provisioning—provisions Oracle RAC 11g release 2 (11.2) and grid infrastructure. This procedure also introduces 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 (formerly OracleMetaLink), to download the latest prerequisites and tools for Oracle RAC provisioning.
The existing One-Click Extend Cluster Database capability now supports Oracle RAC 11g release 2 (11.2) stack.
The existing Delete/Scale down Oracle Real Application Clusters capability is certified with Oracle RAC 11g release 2 (11.2) clusters.
The existing Oracle Database Provisioning procedure now supports provisioning of single instances of Oracle Database 11g release 2 (11.2).
A new deployment procedure—Oracle Grid Infrastructure Provisioning for Standalone Servers—has been introduced to provision Oracle Grid Infrastructure 11g release 2 (11.2) for single-instance databases.
The Cluster Database Home page shows all of the instances in the Oracle RAC database and provides an aggregate collection of several Oracle RAC-specific statistics 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.
This section includes the following topics:
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 RAC database. Or you can create a job at the instance level to run on the specific instance for which you created it. In the event of a failure, recurring jobs can run on a surviving 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,
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:
Click Targets and click the database for which you want to create the job.
Log in to the target database.
When Oracle Enterprise Manager displays the Database Home page, click Maintenance.
Complete the Enterprise Manage Job Wizard panels to create the job.
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.
See Also:Oracle Technology Network for an example of configuring alerts in Oracle RAC and the Oracle Database PL/SQL Packages and Types Reference for information about using packages to configure thresholds
You can define blackouts for all managed targets of an Oracle RAC database to prevent alerts from occurring while performing maintenance. You can define blackouts for an entire cluster database or for specific cluster database instances.