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Oracle9i Real Application Clusters Administration
Release 2 (9.2)

Part Number A96596-01
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When you execute the Discover Node command from the Console, the Management Server contacts the Oracle Intelligent Agent installed on that node to discover the Oracle services installed on the node. The Management Server then places the new information in the repository, and updates the hierarchical tree in the Navigator window of the Console, displaying a broad view of all nodes and their respective services.

cache coherency

The synchronization of data in multiple caches so that reading a memory location by way of any cache will return the most recent data written to that location by way of any other cache. Sometimes called cache consistency.

Cache Fusion

A diskless cache coherency mechanism in Real Application Clusters that provides copies of blocks directly from a holding instance's memory cache to a requesting instance's memory cache.


A set of instances that cooperates to perform the same task.

cluster database

The generic term a Real Application Clusters database.

clustered database

See cluster database.


See cluster database.

Cluster Manager (CM)

An operating system-dependent component that discovers and tracks the membership state of each node by providing a common view of membership across the cluster. The CM also monitors process health, specifically the health of the database instance. The Global Enqueue Service Monitor (LMON), a background process that monitors the health of the Global Cache Service (GCS), registers and de-registers from the CM.


See: Cluster Manager (CM).

connect descriptor

A specially formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.

connect-time failover

See: failover.

connection load balancing

A feature that balances the number of active connections among various instances and shared server dispatchers for the same service. Because of service registration's ability to register with remote listeners, a listener is always aware of all instances and dispatchers regardless. This way, a listener can sends an incoming client request for a specific service to the least loaded instance and least loaded dispatcher regardless of its location.


The Oracle Enterprise Manager Console gives you a central point of control for the Oracle environment through an intuitive graphical user interface (GUI) that provides powerful and robust system management. The Console provides menus, tool bars, and launch palettes that enable access to Oracle tools. The Console consists of four separate windows. See also: Navigator Window,Group Window, Event Management Window, and job window.


Disk and Execution Monitor. A program that is not invoked explicitly, but lies dormant waiting for some condition to occur.

Database Configuration Assistant (DBCA)

An Oracle tool for creating and deleting databases and for managing database templates.

dedicated server

A server that requires a dedicated server process for each user process. There is one server process for each client. Oracle Net sends the address of an existing server process back to the client. The client then resends its connect request to the server address provided. Contrast with shared server.

decision support system (DSS)

Database and application environments that help with decision support or data warehouse systems.


A process that enables many clients to connect to the same server without the need for a dedicated server process for each client. A dispatcher handles and directs multiple incoming network session requests to shared server processes. See also shared server.

distributed recovery

The process of recovery over a cluster.


See: decision support system (DSS).


Shared memory structures that serialize access to database resources and are associated with a session or transaction. In Real Application Clusters, enqueues can be global to a database. Enqueues are local to one instance if Real Application Clusters is not enabled.

Enterprise Manager

See: Oracle Enterprise Manager.

Enterprise Manager Configuration Assistant (EMCA)

A tool for creating, deleting, and modifying Oracle Enterprise Manager configurations and settings.

Event Management Window

Part of the Console. The Event Management window enables the administrator to remotely monitor critical database and system events.

exclusive (X) access mode

A write-only global block access mode. In this mode no other access is allowed.


The process of failure recognition and recovery.

free list groups

Sets of free lists available for use by one or more instances.

General Purpose

The Database Configuration Assistant's preconfigured database template for a hybrid database environment. This template includes datafiles.

Global Cache Service (GCS)

Process that implement Cache Fusion. It maintains the block mode for blocks in the global role. It is responsible for block transfers between instances. The Global Cache Service employs various background processes such as the Global Cache Service Processes (LMSn) and Global Enqueue Service Daemon (LMD).

Global Cache Service Processes (LMSn)

Processes that manage remote Global Cache Service (GCS) messages. Real Application Clusters provides for up to 10 Global Cache Service Processes. The number of LMSn varies depending on the amount of messaging traffic among nodes in the cluster.

Global Cache Service (GCS) resources

Global resources that coordinate access to data blocks in the buffer caches of multiple Real Application Clusters instances to provide cache coherency.

global database name

The full name of the database that uniquely identifies it from any other database. The global database name is of the form database_name.database_domain--for example: OP.US.ORACLE.COM

global dynamic performance views (GV$)

Dynamic performance views storing information about all open instances in a Real Application Clusters cluster. (Not only the local instance.) In contrast, standard dynamic performance views (V$) only store information about the local instance.

Global Enqueue Service (GES)

A service that coordinates enqueues that are shared globally.

Global Enqueue Service Daemon (LMD)

The resource agent process that manages requests for Global Cache Service (GCS) resources to control access to blocks. The LMD process also handles deadlock detection and remote resource requests. Remote resource requests are requests originating from another instance.

Global Enqueue Service Monitor (LMON)

The background LMON process monitors the entire cluster to manage global resources. LMON manages instance deaths and the associated recovery for the Global Cache Service (GCS). In particular, LMON handles the part of recovery associated with global resources. LMON-provided services are also known as Cluster Group Services.

Globalization Support

An architecture that stores, processes, and retrieves data in native languages. It ensures that database utilities and error messages, sort order, date, time, monetary, numeric, and calendar conventions automatically adapt to the native language and locale.

global resources

Inter-instance synchronization mechanisms that provide cache coherency for Real Application Clusters. The term can refer to both Global Cache Service (GCS) resources and Global Enqueue Service (GES) resources.

Global Services Daemon (GSD)

A component that receives requests from SRVCTL to execute administrative job tasks, such as startup or shutdown. The command is executed locally on each node, and the results are returned to SRVCTL. GSD is installed on the nodes by default.

Group Window

Part of the Console. The Group window provides a customized graphical representation of key objects. It is created by the administrator.


See Global Services Daemon (GSD).


See: global dynamic performance views (GV$).

high availability

Systems with redundant components that provide consistent and uninterrupted service, even in the event of hardware or software failures. This involves some degree of redundancy.


A hybrid database is one that has both OLTP and Data Warehouse processing characteristics. See General Purpose.


A parameter designating the continuation file of an initialization parameter file.

initialization parameter file

Files that contains information to initialize the database such as spfile.ora, initdbname.ora and initsid.ora.


An instance initialization parameter file that contains parameters unique for an instance and points to initdbname.ora for database parameters.


A common database initialization parameter file shared among the instance that contains database parameters.


For a Real Application Clusters database, each node within a cluster usually has one instance of the running Oracle software that references the database. When a database is started, Oracle allocates a memory area called the System Global Area (SGA) and starts one or more Oracle processes. This combination of the SGA and the Oracle processes is called an instance. Each instance has unique Oracle System Identifier (sid), instance name, rollback segments, and thread ID.

instance membership recovery (IMR)

The method used by Real Application Clusters guaranteeing that all cluster members are functional or active. IMR polls and arbitrates the membership. Any members that do not show a heartbeat by way of the control file or who do not respond to periodic activity inquiry messages are presumed terminated.

instance name

Represents the name of the instance and is used to uniquely identify a specific instance when clusters share common services names. The instance name is identified by the INSTANCE_NAME parameter in the instance initialization file, initsid.ora. The instance name is the same as the Oracle System Identifier (sid.) See also: Oracle system identifier (sid).

instance number

A number that associates extents of data blocks with particular instances. The instance number enables you to start up an instance and ensure that it uses the extents allocated to it for inserts and updates. This will ensure that it does not use space allocated for other instances.

Intelligent Agent

See: Oracle Intelligent Agent.


The communication link between nodes.

Inter-Process Communication (IPC)

A high-speed operating system-dependent transport component. The IPC transfers messages between instances on different nodes. Also referred to as the interconnect.

job window

Part of the Console. The Job window enables the administrator to automate repetitive activities.


A low-level serialization mechanism that protects in-memory data structures in the System Global Area (SGA). Latches do not protect datafiles, are automatic, and are held for a very short time in exclusive mode. Because latches are synchronized within a node, they do not facilitate internode synchronization.


See Lightweight Directory Access Protocol (LDAP).

Lightweight Directory Access Protocol (LDAP)

A protocol for accessing on-line directory services.


A process that resides on the server to listen for incoming client connection requests and manage the traffic to the server. When a client requests a network session with a server a listener receives the request. If the client information matches the listener information, then the listener grants a connection to the server.


A listener configuration file that identifies the protocol addresses on which the listener is accepting connection requests and the services the listener listens for.


See Global Enqueue Service Daemon (LMD).


See Global Enqueue Service Monitor (LMON).


See Global Cache Service Processes (LMSn).

Management Server

The Oracle Enterprise Manager Management Server provides centralized intelligence and distributed control between the Console and the managed nodes, and processes system management tasks sent by the Console and administers the distribution of these tasks across the enterprise. The Management Server stores all system data, application data, and information about the state of managed nodes in a repository. The repository is a set of tables stored in a database. High performance and scalability is ensured because the workload is automatically shared and balanced when there are multiple Management Servers.

master free list

A list of blocks containing available space drawn from any extent in a table.

mean time between failures (MTBF)

The average time (usually expressed in hours) that a component works without failure. It is calculated by dividing the total number of failures into the total number of operating hours observed. The term can also mean the length of time a user can reasonably expect a device or system to work before an failure occurs.

mean time to failure (MTTF)

The average period of time that a component will work until failure.

mean time to recover (MTTR)

The average time that it takes to get a failed piece of hardware back on line. Outside the context of Real Application Clusters, the acronym MTTR is also used for Mean Time to Repair.


See: mean time between failures (MTBF).


See: mean time to failure (MTTF).


See: mean time to recover (MTTR).

multiple oracle homes

The capability of having more than one Oracle home directory on a machine.


See: null (N).

naming method

The method used by a client application to resolve a net service name to a connect descriptor.

Navigator Window

Part of the Console. The Navigator window contains an object browser that provides an organized, consistent, and hierarchical view of the database objects in the network.

net service name

A simple name for a service that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a net service name in a connect string for the desired service.

network file system (NFS)

A protocol developed by Sun Microsystems, and defined in RFC 1094, that enables a computer to access files over a network as if the files were on local disks.


A node is a machine on which an instance resides.

null (N)

Null indicates that an access mode is not assigned to a block or resource.


See: online transaction processing (OLTP).

online transaction processing (OLTP)

The processing of transactions by computers in real time.

operating system-dependent (OSD) clusterware

Software that consists of several software components developed by Oracle or by other vendors. The OSD clusterware maps the key operating system and clusterware services required for proper operation of Real Application Clusters.

Oracle Enterprise Edition

Oracle Enterprise Edition is an Object-Relational Database Management System (ORDBMS). It provides the applications and files to manage a database. All other Real Application Clusters components are layered on top of Oracle Enterprise Edition.

Oracle Enterprise Manager

A system management tool that provides an integrated solution for centrally managing your heterogeneous environment. Oracle Enterprise Manager combines a graphical Console, Management Server, Oracle Intelligent Agent, repository database, and tools to provide an integrated, comprehensive systems management platform for managing Oracle products.

Oracle Intelligent Agent

A process that runs on each of the nodes. It functions as the executor of jobs and events sent by the Console by way of the Management Server. High availability is ensured since the agent can function regardless of the status of the Console or network connections.

Oracle Net

A software component that enables connectivity. It includes a core communication layer called the Oracle Net foundation layer and network protocol support. Oracle Net enables services and their applications to reside on different computers and communicate as peer applications.

Oracle Performance Manager

An add-on application for Oracle Enterprise Manager that offers tabular and graphic performance statistics for Real Application Clusters. The statistics represent the aggregate performance for all instances running on Real Applications.

Oracle Real Application Clusters

A breakthough architecture that enables clusters to access a shared database. Real Application Clusters includes the software component that provides the necessary Real Application Clusters scripts, initialization files, and datafiles to make the Oracle9i Enterprise Edition an Oracle9i Real Application Clusters database.

Oracle system identifier (sid)

The Oracle System Identifier (sid) identifies a specific instance of the running Oracle software. For an Real Application Clusters database, each node within the cluster has an instance referencing the database.

The database name, specified by the DB_NAME parameter in the INITDB_NAME.ORA file, and unique thread ID make up each node's sid. The thread ID starts at 1 for the first instance in the cluster, and is incremented by 1 for the next instance, and so on. See also: instance name.


See operating system-dependent (OSD) clusterware.

Oracle Universal Installer (OUI)

A tool to install the Oracle relational database software. You can also use the Oracle Universal Installer to launch the Database Configuration Assistant (DBCA).

parameter file (PFILE)

A file used by the Oracle server that provide specific values and configuration settings that are used on database startup. The keyword PFILE is used in the startup command.

Performance Manager

See: Oracle Performance Manager.

preferred credentials

Each Oracle Enterprise Manager administrator can set up specific user names, passwords, and roles for nodes, listeners, databases, and other services that you administer in the network.

Real Application Clusters

See Oracle Real Application Clusters.

Recovery Manager (RMAN)

An Oracle tool that enables you to back up, copy, restore, and recover datafiles, control files, and archived redo logs. It is included with the Oracle server and does not require separate installation. You can invoke RMAN as a command line utility from the operating system (O/S) prompt or use the GUI-based Enterprise Manager Backup Manager.

repository database

A set of tables in an Oracle database that stores data required by Oracle Enterprise Manager. This database is separate from the database on the nodes.


See: Recovery Manager (RMAN).


The ability to add additional nodes to Real Application Clusters applications and achieve markedly improved scale-up and speed-up.

seed database

A preconfigured, ready-to-use database that re quires minimal user input to create. See also: starter database.

server clustering

See Real Application Clusters.

Server Control (SRVCTL) Utility

Server Management uses the SRVCTL utility (installed on each node) to manage configuration information that is used by some Oracle tools. For example, SRVCTL serves as a single point of control between the Oracle Intelligent Agent and the nodes. Only one node's Oracle Intelligent Agent is used to communicate with SRVCTL. SRVCTL on that node then communicates to the other nodes through Oracle Net.

Server Management (SRVM)

Server Management (SRVM) comprises the components required to operate Oracle Enterprise Manager in Real Application Clusters. The SRVM components, such as the Intelligent Agent, Global Services Daemon, and SRVCTL, enable you to manage cluster databases running in heterogeneous environments through an open client/server architecture using Oracle Enterprise Manager.

server parameter file

A binary parameter file that resides on the Oracle Server. This file contains parameter settings that are both global and instance-specific. These parameter settings are persistent across instance shutdown and instance startup events.

service discovery

When you execute the Discover Node command from the Console, the Management Server contacts the Oracle Intelligent Agent installed on that node to discover the Oracle services installed on the node. The Management Server then places the new information in the repository and updates the hierarchical tree in the Navigator window of the Console, displaying a broad view of all nodes and their respective services.

service name

A logical representation of a database. This is the way a database is presented to clients. A database can be presented as multiple services and a service can be implemented as multiple database instances. The service name is a string that is the global database name, a name comprised of the database name (DB_NAME) and domain name (DB_DOMAIN), entered during installation or database creation.

service registration

A feature whereby PMON automatically registers information with a listener. Because this information is registered with the listener, the listener.ora file does not need to be configured with this static information.

shared current (scur)

The buffer state name for shared access mode to a block.

shared mode (s)

A protected read block access mode. No writes are allowed in shared mode. In shared mode, any number of users can have simultaneous read access to a resource. See also: exclusive (X) access mode.

shared server

A server that is configured to allow many user processes to share very few server processes, so the number of users that can be supported is increased. With shared server configurations, many user processes connect to a dispatcher.


See: Oracle system identifier (sid).


The binary parameter file that resides on the Oracle Server.

snapshot control file

RMAN creates a snapshot control file to resynchronize from a read-consistent version of the control file. This is a temporary snapshot control file. RMAN only needs a snapshot control file when resynchronizing with the recovery catalog or when making a backup of the current control file.

sqlnet.ora File

A configuration file for the client or server that specifies:

The sqlnet.ora file typically resides in the $ORACLE_HOME/network/admin directory on UNIX platforms and in the %ORACLE_HOME%\network\admin directory on Windows platforms.


See Server Control (SRVCTL) Utility.

starter database

See: seed database.


A database administration role that contains all system privileges with the ADMIN OPTION, and the SYSOPER system privilege. SYSDBA also permits CREATE DATABASE and time-based recovery.


A database administration role that permits a database administrator to perform any of the following commands: STARTUP, SHUTDOWN, ALTER DATABASE OPEN/MOUNT, ALTER DATABASE BACKUP, ARCHIVE LOG, and RECOVER. SYSOPER includes the RESTRICTED SESSION privilege.


See: transparent application failover (TAF).


Each Oracle instance has its own set of online redo log groups. These groups are called a thread of online redo. In non-Real Application Clusters environments, each database has only one thread that belongs to the instance accessing it. In Real Application Clusters environments, each instance has a separate thread, that is, each instance has its own online redo log. Each thread has its own current log member.

thread number

The number of the redo thread to be used by an instance as specified by the THREAD initialization parameter or the THREAD clause in the ALTER DATABASE ADD LOGFILE statement. You can use any available redo thread number but an instance cannot use the same thread number as another instance.

tnsnames.ora file

A file that contains net service names. This file is needed on clients, nodes, the Console, and the Oracle Performance Manager machine.

transparent application failover (TAF)

A runtime failover for high-availability environments, such as Real Application Clusters and Oracle Real Application Clusters Guard, TAF refers to the failover and re-establishment of application-to-service connections. It enables client applications to automatically reconnect to the database if the connection fails, and optionally resume a SELECT statement that was in progress. This reconnect happens automatically from within the Oracle Call Interface (OCI) library.

Virtual Interface Architecture (VIA)

A memory-based networking interface.


See: exclusive (X) access mode.

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