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Network Time Protocol (NTP)
An Internet standard protocol, built on top of TCP/IP, that ensures the accurate
synchronization to the millisecond of the computer clock times in a network of
Network Interface Card (NIC)
A card that you insert into a computer to connect the computer to a network.
A node is a machine on which an instance resides.
Oracle Cluster File System (OCFS)
The Oracle proprietary cluster file system software that is available for Linux and
Oracle Cluster Registry (OCR)
The RAC configuration information repository that manages information about the
cluster node list and instance-to-node mapping information. The OCR also manages
information about Oracle Clusterware resource profiles for customized applications.
Object Link Manager (OLM)
The Oracle interface that maps symbolic links to logical drives and displays them in
the OLM graphical user interface.
A UNIX-based process that manages the Cluster Synchronization Services (CSS)
daemon. Manages cluster node membership and runs as oracle user; failure of this
process results in cluster restart.
Oracle Interface Configuration Tool (OIFCFG)
A command-line tool for both single-instance Oracle databases and RAC databases
that enables you to allocate and de-allocate network interfaces to components, direct
components to use specific network interfaces, and retrieve component configuration
information. The Oracle Universal Installer (OUI) also uses OIFCFG to identify and
display available interfaces.
Oracle Notification Services (ONS)
A publish and subscribe service for communicating information about all FAN events.
A UNIX-based process monitor for a cluster. Note that this process will only appear on
platforms that do not use vendor clusterware with Oracle Clusterware.
Oracle-provided clusterware that manages cluster database processing including node
membership, group services, global resource management, and high availability
Oracle Universal Installer (OUI)
A tool to install Oracle Clusterware, the Oracle relational database software, and the
Oracle Real Application Clusters software. You can also use the Oracle Universal
Installer to launch the Database Configuration Assistant (DBCA).
A disk drive that does not yet have a file system set up. Raw devices are used for Real
Application Clusters since they enable the sharing of disks. See also raw partition.
A portion of a physical disk that is accessed at the lowest possible level. A raw
partition is created when an extended partition is created and logical partitions are
assigned to it without any formatting. Once formatting is complete, it is called a
cooked partition. See also raw device.
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
Runtime Connection Load Balancing
Connection pool load balancing enables Oracle to make intelligent service connection
decisions based on the connection pool that provides the optimal service for the
requested application based on current workloads. The JDBC, ODP.NET, and OCI
clients are integrated with the load balancing advisory; you can use any of these three
client environments to provide connection pool load balancing.
The ability to add additional nodes to Real Application Clusters applications and
achieve markedly improved scale-up and speed-up.
Secure Shell (SSH)
A program for logging into a remote computer over a network. You can use SSH to
execute commands on a remote machine and to move files from one machine to
another. SSH uses strong authentication and secure communications over insecure
Server Control (SRVCTL) Utility
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.
Entities that you can define in RAC databases that enable you to group database
workloads and route work to the optimal instances that are assigned to offer the
A database architecture in which all instances share access to all of the data.
Services that run on only one instance at any one time. By defining the Distributed
Transaction Property (DTP) property of a service, you can force the service to be a
split brain syndrome
Where two or more instances attempt to control a cluster database. In a two-node
environment, for example, one instance attempts to manage updates simultaneously
while the other instance attempts to manage updates.
system identifier (SID)
The Oracle system identifier (SID) identifies a specific instance of the running Oracle
software. For a Real Application Clusters database, each node within the cluster has an
instance referencing the database.
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.
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.
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.
A file that manages information about node membership.