|Oracle Real Application Clusters Guard Concepts and Administration Guide
Release 3.2.1 for Windows NT and Windows 2000
Part Number A95197-01
The measure of the ability of a system or resource to provide the desired service when required. Availability is measured in terms of the percentage of time the device is accessible out of the total time it is needed.
The application that provides all user-oriented activities, such as character or graphical user display, screen control, data presentation, application flow, and other application-specific tasks.
A group of two or more independent computing systems that operate as a single virtual system.
A node-independent network name that identifies a cluster and is used for cluster-related system management.
An application that is designed to automatically reconnect to a surviving cluster node when a failover occurs. These cluster-aware applications handle all details associated with reconnecting to the surviving node and replaying any transactions that might have been lost when the failure occurred.
A Windows system that is a member of a cluster.
A resource that is configured and managed on a cluster node. See also resource.
An operation in which a client connect request is forwarded to another listener if the first listener is not responding or if the database instance associated with that listener is unavailable.
A file that records the physical structure of a database and contains the database name, the names and locations of associated databases and online redo log files, the time stamp of the database creation, the current log sequence number, and checkpoint information.
A file that contain the contents of logical database structures, such as tables and indexes. One or more data files form a logical unit of storage called a tablespace. A data file can be associated with only one tablespace, and only one database.
A nontransient database instance state where user operations appear to neither succeed nor fail.
The default n-node Oracle Real Application Clusters deployment is the default environment. All nodes of the cluster participate in client transaction processing, and client sessions can be load balanced at connect time. Response time is optimized for available cluster resources, such as CPU and memory, by distributing the load across cluster nodes to create a highly available environment.
In the event of an instance failure, an instance on another node performs the necessary recovery actions and Oracle Real Application Clusters Guard applies the instance restart policies defined for the database. If Oracle Real Application Clusters Guard cannot (or does not) restart the failed instance, the database clients on the failed instance can be load balanced across the n - 1 surviving instances on the cluster. The increased load on each of the surviving instances can be minimized and availability increased by keeping response times within acceptable bounds. In this configuration, the database application workload can be distributed across all nodes and, therefore, this configuration provides optimal use of cluster system resources.
The process of moving a group from one node to another node. This process can either be planned (for upgrades and maintenance, for example) or unplanned (due to system or resource failure, for example).
The server node to which a group is moved when a group failover occurs.
A user-specified time period in which the cluster software should continue to try to move cluster resources from one node to another before discontinuing the failover process and taking the resources offline. See also group failover policy.
The maximum number of times the cluster software should attempt to move resources from one node to another during the time period (failover period) that you specify. After reaching the specified failover threshold, the cluster software will stop the failover process and take the resources offline. See also group failover policy.
The inability of a computing component to perform its function correctly.
A Windows service that is supported by the generic service resource DLL provided with Microsoft Cluster Server (MSCS). The generic service resource DLL is used to configure standard Windows services (such as IP addresses, physical disks, and some applications) as resources in a cluster.
A component of Oracle Services for MSCS that manages issues and policies that affect Oracle Real Application Clusters database instances as a set, such as instance restart policies and resolving database hangs. The status of each Oracle Real Application Clusters database instance is communicated to the global monitor so that the monitor has a view of all of the database instances on the system.
A logical collection of cluster resources that forms a minimal unit of failover. In a failover situation, the group of resources is moved together to a failover node. A group resides on only one cluster node at a time. A group may have more than one preferred owner node. See also instance group.
The process of taking a group of cluster resources offline on one node and attempting to bring them back online on another node. This process can either be planned (for upgrades and maintenance, for example) or unplanned (due to system or resource failure, for example).
A user-specified plan that determines two parameters: the time period in which the cluster software should continue to move a group of resources from one node to another (failover period), and the maximum number of times group failover should occur during the failover period (failover threshold). See also failover period and failover threshold.
See private interconnect.
A name that represents the specific IP address on a network. In Microsoft Cluster Server (MSCS), the host name is mapped to a network name resource. See also network name.
A combination of System Global Area (SGA) and one or more Oracle database server processes. When a database is started on a database server, the Oracle database server allocates SGA and starts one or more Oracle database server processes. The memory and processes of an instance efficiently manage the associated database's data and serve the database users. Users can connect to any instance to access information within an Oracle Real Application Clusters database. Each instance has a unique database system identifier (SID), instance name, instance number, rollback segments, and thread ID.
A logical collection of cluster resources that forms a minimal unit of failover for a database instance. In a failover situation, the group of resources is moved together to a failover node. An instance group resides on only one cluster node at a time and has only one preferred owner node. See also group.
See private interconnect.
The Internet Protocol (IP) address. An IP address takes the form n.n.n.n, for example, 184.108.40.206.
A service that receives requests by clients and redirects them to the appropriate database instance.
An event that occurs when a large number of users connect to a database instance within a small window of time.
Microsoft Corporation software that provides the capability to cluster individual nodes that are running Windows NT Enterprise Edition, Windows 2000 Advanced Server, or Windows 2000 Datacenter Server.
Network information that describes the network and connection data of an Oracle database. More than one net service name can be defined for an Oracle database. Prior to Oracle8i, a net service name was referred to as a service name entry.
The Microsoft Cluster Server (MSCS) term for a NetBIOS name, which translates into a specific IP address on a network. See also host name.
A computing system that is a member of a cluster.
An event that occurs when many more than the typical load of queries are executed against a database instance within a given time period.
A possible owner node for an instance group is any cluster node where Oracle Services for MSCS is installed.
The set of all nodes on which Oracle Services for MSCS has been installed, less any nodes that you explicitly remove from the set using the Nodes tab for the group through Oracle Real Application Clusters Guard Manager.
The node on which you want a group to reside when all cluster nodes that are possible owners are up and running. See also failover node.
In a primary/secondary Oracle Real Application Clusters database deployment, the instance through which clients access the database. See also secondary instance.
In a primary/secondary instance deployment of Oracle Real Application Clusters databases, the instance that mounts the database first assumes the primary role. It performs the work requested by the application sessions. If the primary instance fails or is shut down, then another instance assumes the primary instance role. See also secondary instance role.
A deployment option for Oracle Real Application Clusters databases in which the primary instance is the instance through which clients access the database. The secondary instance provides backup services to the primary instance if the primary instance fails or is shut down. See also primary instance, secondary instance, and default n-node deployment.
A network connection that is dedicated to intracluster communication. The private interconnect is also referred to as a heartbeat connection, because it allows one node to detect the availability or unavailability of another node. The private interconnect is distinct from the public interconnect. See also public interconnect.
A network connection (such as a LAN or WAN) that connects clients to the cluster. See also private interconnect.
A voting mechanism used to guarantee that specific data necessary for recovery can be maintained consistently among all cluster members. This mechanism involves a special storage resource called the quorum resource. The quorum is also used to establish the cluster. See also quorum resource.
The quorum-capable storage resource selected to maintain the configuration data necessary for recovery of the cluster. The quorum resource is generally accessible to other cluster resources so that any cluster node has access to the most recent changes to the configuration data. See also quorum.
The unformatted devices on shared disk arrays as used by Oracle Real Application Clusters databases on Windows NT and Windows 2000 platforms.
An Oracle software product that allows multiple database instances to access a shared database of datafiles.
A file that contains a record of all changes made to data in the database buffer cache. If an instance failure occurs, the redo log files are used to recover the modified data that was in memory.
Duplicate or extra computing components that safeguard the integrity of a computing system.
A physical or logical component that is available to a computing system. For example, a resource can be a disk, a network IP address, an Oracle database instance, or a listener. See also cluster resource.
Relationships between resources in a group that define the order in which the cluster software brings those resources online and offline.
A policy that specifies whether or not a resource failure should result in a group failover.
A policy that specifies whether or not the cluster software should attempt to restart a failed resource on its current node, and if so, how many attempts within a given time period should be made to restart it.
In a primary/secondary Oracle Real Application Clusters deployment, the instance that provides backup services to the primary instance in case the primary instance fails. See also primary instance.
In a primary/secondary Oracle Real Application Clusters deployment, the second instance to mount the database assumes the secondary instance role. The instance with the primary role performs the work that is requested by application sessions, but selected tasks, such as reporting and planned operations, can be performed by the instance with the secondary instance role. See also primary instance role.
See net service name.
A cluster configuration in which all cluster nodes are cabled physically to the same disks, but only one node can access a given disk at a time for either read or write activity.
An I/O connection on which the cluster disks are accessible from all nodes in a cluster.
An installation method that allows you to install software by supplying input to Oracle Universal Installer with a response file.
The ability of client applications to automatically reconnect to a database and resume work after a failover occurs.
A network address at which available resources in a group can be accessed, regardless of the cluster node hosting those resources. A virtual address on an MSCS cluster consists of a network name and associated IP address.
A group with one or more virtual addresses.