A failover configuration where each system runs a service group. If either system fails, the other one takes over and runs both service groups. Also symmetric configuration.

A failover configuration consisting of one service group on a primary system, and one dedicated backup system. Also asymmetric configuration.

Any storage resource in the network that is ready to be allocated for use by hosts and applications. Also AddrUnit or AU.

See also LUN

The total amount of addressable storage in LUNs that is designated for use by specific hosts. A LUN is considered allocated when a host operating system has written a device handle for the LUN (in other words, claimed the LUN) or when the array has masked the LUN to a specific target.

Contrast with unallocated storage

A program or group of programs designed to perform a specific task. Oracle Database and Symantec NetBackup are examples of applications.

See Symantec Product Authentication Service.

A device that connects and passes packets between two segments of a storage network that use the same communications protocol.

See also router

The amount of storage an object can allocate or use.

Storage for which at least one host's operating system has created a device handle.

Contrast with unclaimed storage

A set of hosts (each termed a node) that share a set of disks and are connected by a set of redundant heartbeat networks.

Communication between clusters using either of the two core communication protocols defined by Veritas Cluster Server: GAB and LLT. The communication takes place by means of heartbeat signals sent between systems or fast kernel-to-kernel broadcasts.

Physical storage that has been formatted and is ready to be apportioned into RAID groups.

Contrast with unconfigured storage

The name the operating system uses to identify a storage resource (known as an addressable unit or LUN), and the correct means (driver, system call) to access it. Also OS handle.

A collection of disks that share a common configuration. A disk group configuration is a set of records containing detailed information on existing Veritas Volume Manager objects (such as disk and volume attributes) and their relationships. Each disk group has an administrator-assigned name and an internally defined unique ID. The root disk group (rootdg) is a special private disk group that always exists.

A feature of Veritas Volume Manager that provides greater reliability and better performance by using path failover and load balancing for multiported disk arrays connected to host systems through multiple paths. DMP detects the various paths to a disk using a mechanism that is specific to each supported array type. DMP can also differentiate between different enclosures of a supported array type that are connected to the same host system.

A notification that indicates when an action, such as an alert or a change in state, has occurred for one or more objects on the storage network.

A backup operation that automatically switches to a standby database, server, or network if the primary system fails or is temporarily shut down for servicing.

A means of organizing the addressable (LUN) storage of one or more physical or virtual disks to give users and applications a convenient way of organizing files. File systems appear to users and applications as directories arranged in a hierarchy.

A set of software instructions set permanently in a device's memory.

Gigabit interface converter. A widely used transceiver module for Fibre Channel. A GBIC is modular and hot-swappable and can be either copper or optical.

A VCS service group that spans across two or more clusters. The ClusterList attribute for this group contains the list of clusters over which the group spans.

A communication mechanism of the VCS engine that manages cluster membership, monitors heartbeat communication, and distributes information throughout the cluster.

A common connection point for devices in the storage network. The hub may be unmanaged, IP-managed, or FC-managed. An unmanaged hub is passive in the sense that it serves simply as a conduit for data, moving the data from one storage resource to another. IP-managed and FC-managed hubs are intelligent, containing features an administrator can use to monitor the traffic passing through the hub and configure each port in the hub.

See LUN.

A unique and discrete addressable unit or logical volume that may reside inside one or more simple or array storage devices. LUNs are exposed to the outside world through an addressing scheme presented to the host as SCSI LUN numbers. Each LUN has a unique device handle and represents a logical volume.

An object in a network. In Veritas Cluster Server, node refers specifically to one of any number of hosts in a cluster. See also object.

A single, unique addressable entity on a storage network. It is possible for objects to be present within objects. For example, while a tape array is an object, each individual tape drive within the array is also an object. A host is an object, and the HBA inside the host is also an object. Each object has one or more attributes and can be a member of one or more zones.

A key which uniquely identifies an object in the discovery data store. OIDs are represented in XML files as hexadecimal strings with a maximum length of 128 characters.

The physical components of a fabric, including all switches and all other SAN objects. You can configure one or more virtual fabrics - each one isolated from the others - based on the hardware components in the physical fabric.

A set of rules, or configuration settings, that are applied across a number of objects in the storage network. You establish policies to help you monitor and manage the network. Each policy associates certain sets of conditions with storage resources and defines actions to be taken when these conditions are detected.

Redundant Array of Independent Disks. A set of techniques for managing multiple disks for cost, data availability, and performance.

See also mirroringstriping

Any of the individual components that work together to provide services on a network. A resource may be a physical component such as a storage array or a switch, a software component such as Oracle8i or a Web server, or a configuration component such as an IP address or mounted file system.

Acronym for "storage area network." A network linking servers or workstations to devices, typically over Fibre Channel, a versatile, high-speed transport. The storage area network (SAN) model places storage on its own dedicated network, removing data storage from both the server-to-disk SCSI bus and the main user network. The SAN includes one or more hosts that provide a point of interface with LAN users, as well as (in the case of large SANs) one or more fabric switches and SAN hubs to accommodate a large number of storage devices.

Small Computer Systems Interface. A hardware interface that allows for the connection of multiple peripheral devices to a single expansion board that plugs into the computer. The interface is widely used to connect personal computers to peripheral devices such as disk and media drives.

A technique used to protect a cluster from a preexisting network partition. By default, when a system comes up, it is not seeded. Systems can be seeded automatically or manually. Only systems that have been seeded can run VCS. Systems are seeded automatically only when an unseeded system communicates with a seeded system or when all systems in the cluster are unseeded and able to communicate with each other.

See network partition

A collection of resources working together to provide application services to clients. It typically includes multiple resources, hardware- and software-based, working together to provide a single service.

Simple Mail Transfer Protocol, a commonly used protocol for sending email messages between servers.

A method of mirroring volumes and qtrees on NetApp unified storage devices. With SnapMirror, a user can schedule or initiate data transfers, request information about transfers, update a mirror, and manage mirrors.

See mirroring

A point-in-time image of a volume or file system that can be used as a backup.

The Simple Network Management Protocol for Internet network management and communications used to promote interoperability. SNMP depends on cooperating systems that must adhere to a common framework and a common language or protocol.

A layout technique that spreads data across several physical disks by mapping the data to successive media, known as stripes, in a cyclic pattern. Also RAID Level 0.

A network device to which nodes attach and which provides high-speed switching of node connections via link-level addressing.

The physical hardware on which data and applications reside, and the connections between them.

The physical or logical arrangement of resources on the storage network and the connections between them.

Storage to which data has not been written.

Contrast with used storage

A unique IP address associated with a VCS cluster. This address can be used on any system in the cluster, along with other resources in the VCS cluster service group. A virtual IP address is different from a system's base IP address, which corresponds to the system's host name.

See also IP address

Representing one or more objects, services, or functions as a single abstract entity so that they can be managed or acted on collectively. An example of virtualization is the creation of a virtual fabric from a switch and associated storage resources as a means of controlling access and increasing scalability in the storage network.