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Glossary



ACL

Access control list. A list that contains the users' or groups' access rights to each share.



adapter card

A SCSI card, network card, hot swap adapter card, serial adapter card, or VGA adapter that plugs into an expansion slot.



address resolution

The procedure for determining a Media Access Control (MAC) address corresponding to the address of a LAN or WAN destination.



administration host

The client you specify during system setup for managing your storage system. The setup program automatically configures the storage system to accept telnet and rsh connections from this client, to give permission to this client for mounting the / and /home directories, and to use this client as the mail host for sending AutoSupport email messages. At any time after you run the setup program, you can configure the storage system to work with other clients in the same way as it does with the administration host.



agent

A Data ONTAP process that gathers status and diagnostic information and forwards it to NMSs.



appliance

A device that performs a well-defined function and is easy to install and operate.



ATM

Asynchronous Transfer Mode. A network technology that combines the features of cell-switching and multiplexing to offer reliable and efficient network services. ATM provides an interface between devices such as workstations and routers, and the network.



authentication

A security step performed by a domain controller for the storage system's domain, or by the storage system itself, using its /etc/passwd file.



AutoSupport

A NetApp storage system daemon that triggers email messages from the customer site to technical support or another specified email recipient when there is a potential storage system problem.



big-endian

A binary data format for storage and transmission in which the most significant bit or byte comes first.



CIFS

Common Internet File System. A protocol for networking PCs.



client

A computer that shares files on a storage system.



cluster

A pair of storage systems connected so that one system can detect when the other is not working and, if so, can serve the failed system's data.



cluster interconnect

Cables and adapters with which the two storage systems in a cluster are connected and over which heartbeat and WAFL log information are transmitted when both systems are running.



cluster monitor

Software that administers the relationship of storage systems in the cluster through the cf command.



community

A name used as a password by the SNMP manager to communicate with the storage system agent.



console

A terminal that is attached to a storage system's serial port and is used to monitor and manage storage system operation.



copy-on-write

The technique for creating Snapshot copies without consuming excess disk space.



degraded mode

The operating mode of NetApp storage systems when a disk is missing from the RAID array or the batteries on the NVRAM card are low.



disk ID number

A number assigned by the storage system to each disk when it probes the disks at boot time.



disk shelf

A shelf that contains disk drives and is attached to the storage system.



emulated storage system

A software copy of the failed storage system that is hosted by the takeover storage system. The emulated storage system appears to users and administrators like a functional version of the failed storage system. For example, it has the same name as the failed storage system.



Ethernet adapter

An Ethernet interface card.



expansion card

A SCSI card, NVRAM card, network card, hot swap card, or console card that plugs into a storage system expansion slot.



expansion slot

The slots on the system board in which you insert expansion cards.



failed storage system

The physical storage system that has ceased operating. It remains the failed storage system until giveback succeeds.



FDDI adapter

A Fiber Distributed Data Interface (FDDI) interface card.



FDDI-fiber

An FDDI adapter that supports a fiber-optic cable.



FDDI-TP

An FDDI adapter that supports a twisted-pair cable.



FPolicy

Data ONTAP's proprietary file policy feature that provides the ability to control access permissions based on file properties, such as file type.



GID

Group identification number.



giveback

The return of identity from the virtual storage system to the failed storage system, resulting in a return to normal operation; the reverse of takeover.



group

A group of users defined in the storage system's /etc/group file.



heartbeat

A repeating signal transmitted from one NetApp storage system to the other that indicates that the system is in operation. Heartbeat information is also stored on disk.



hot spare disk

A disk installed in NetApp storage systems that can be used to substitute for a failed disk. Before the disk failure, the hot spare disk is not part of the RAID disk array.



hot swap

The process of adding, removing, or replacing a disk while storage systems are running.



hot swap adapter

An expansion card that makes it possible to add or remove a hard disk with minimal interruption to file system activity.



inode

A data structure containing information about files on a storage system and in a UNIX file system.



interrupt switch

A switch on some storage system front panels used for debugging purposes.



LAN Emulation (LANE)

The architecture, protocols, and services that create an Emulated LAN using ATM as an underlying network topology. LANE enables ATM-connected end systems to communicate with other LAN-based systems.



local storage system

The storage system you are logged in to.



magic directory

A directory that can be accessed by name but does not show up in a directory listing. The Snapshot copy directories, except for the one at the mount point or at the root of the share, are magic directories.



mailbox disk

One of a set of disks owned by each NetApp storage system that is used to store the cluster state information of the system. If that storage system stops operating, the takeover system uses the information in the mailbox disks in constructing a virtual storage system. Mailbox disks are also used as file system disks.



mail host

The client host responsible for sending automatic email to technical support when certain storage system events occur.



maintenance mode

An option when booting a storage system from a system boot disk. Maintenance mode provides special commands for troubleshooting hardware and configuration.



MIB

Management Information Base. An ASCII file that describes the information that the agent forwards to NMSs.



MIME

Multipurpose Internet Mail Extensions. A specification that defines the mechanisms for specifying and describing the format of Internet message bodies. An HTTP response containing the MIME Content-Type header allows the HTTP client to start the application that is appropriate for the data received.



MultiStore

An optional NetApp storage system software product that enables you to partition the storage and network resources of a single storage system so that it appears as multiple storage systems on the network.



NDMP

Network Data Management Protocol. A protocol that allows storage systems to communicate with backup applications, and provides capabilities for controlling the robotics of multiple tape backup devices.



network adapter

An Ethernet, FDDI, or Asynchronous Transfer Mode (ATM) adapter.



network management station

See NMS.



NMS

Network Management Station. A host on a network that uses third-party network management application (SNMP manager) to process status and diagnostic information about a storage system.



normal mode

The state of storage systems when there is no takeover in the cluster.



null user

The Windows NT machine account used by applications to access remote data.



NVRAM cache

Nonvolatile RAM in NetApp storage systems, used for logging incoming write data and NFS requests. Improves system performance and prevents loss of data in case of a storage system or power failure.



NVRAM card

An adapter card that contains the NetApp storage system's NVRAM cache.



NVRAM mirror

A synchronously updated copy of the contents of NetApp storage system NVRAM (Nonvolatile Random Access Memory) contents kept on the partner storage system.



panic

A serious error condition causing the storage system to halt. Similar to a software crash in the Windows system environment.



parity disk

The disk on which parity information is stored for the RAID-4 disk drive array. Used to reconstruct data in failed disk blocks or on a failed disk.



partner

From the point of view of the local storage system, the other storage system in the cluster.



partner mode

The method you use to communicate through the command-line interface with the virtual storage system during a takeover.



PCI

Peripheral Component Interconnect. The bus architecture used in newer storage system models.



pcnfsd

A storage system daemon that permits PCs to mount storage system file systems. The corresponding PC client software is called PC-NFS.



PDC

Primary Domain Controller. The domain controller that has negotiated to be, or has been assigned as, the primary authentication server for the domain.



POST

Power-on self-tests. The tests run by storage systems after the power is turned on.



PVC

Permanent Virtual Circuit. A link with a static route defined in advance, usually by manual setup.



qtree

A special subdirectory of the root of a volume that acts as a virtual subvolume with special attributes.



RAID

Redundant array of independent disks. A technique that protects against disk failure by computing parity information based on the contents of all the disks in the array. NetApp storage systems use RAID Level 4, which stores all parity information on a single disk.



RAID disk scrubbing

The process in which the system reads each disk in the RAID group and tries to fix media errors by rewriting the data to another disk area.



SCSI adapter

An expansion card that supports the SCSI disk drives and tape drives.



SCSI address

The full address of a disk, consisting of the disk's SCSI adapter number and the disk's SCSI ID; for example, 9a.1.



SCSI ID

The number of a disk drive on the SCSI chain (0 to 6).



serial adapter

An expansion card for attaching a terminal as the console on some storage system models.



serial console

An ASCII or ANSI terminal attached to a storage system's serial port. Used to monitor and manage storage system operations.



share

A directory or directory structure on the storage system that has been made available to network users and can be mapped to a drive letter on a CIFS client.



SID

Security identifier.



Snapshot copy

An online, read-only copy of the entire file system that protects against accidental deletions or modifications of files without duplicating file contents. Snapshot copies enable users to restore files and to back up the NetApp storage system to tape while the system is in use.



SVC

Switched Virtual Circuit. A connection established through signaling. The user defines the endpoints when the call is initiated.



system board

A printed circuit board that contains the storage system's CPU, expansion bus slots, and system memory.



takeover

The emulation of the failed storage system identity by the takeover storage system in a cluster; the reverse of giveback.



takeover storage system

A storage system that remains in operation after the other storage system stops working and that hosts a virtual storage system that manages access to the failed storage system disk shelves and network connections. The takeover storage system maintains its own identity and the virtual storage system maintains the failed storage system identity.



takeover mode

The method you use to interact with a storage system while it has taken over its partner. The console prompt indicates when the storage system is in takeover mode.



trap

An asynchronous, unsolicited message sent by an SNMP agent to an SNMP manager indicating that an event has occurred on the storage system.



tree quota

A type of disk quota that restricts the disk usage of a directory created by the quota qtree command. Different from user and group quotas that restrict disk usage by files with a given UID or GID.



UID

User identification number.



Unicode

A 16-bit character set standard. It was designed and is maintained by the nonprofit consortium Unicode Inc.



VCI

Virtual Channel Identifier. A unique numerical tag defined by a 16-bit field in the ATM cell header that identifies a virtual channel over which the cell is to travel.



vFiler unit

A virtual NetApp storage system you create using MultiStore, which enables you to partition the storage and network resources of a single storage system so that it appears as multiple storage systems on the network.



VGA adapter

An expansion card for attaching a VGA terminal as the console.



volume

A file system.



VPI

Virtual Path Identifier. An eight-bit field in the ATM cell header that indicates the virtual path over which the cell should be routed.



WAFL

Write Anywhere File Layout. The WAFL file system was designed for NetApp storage systems to optimize write performance.



WINS

Windows Internet Name Service.



workgroup

A collection of computers running Windows NT or Windows for Workgroups that is grouped for browsing and sharing.

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