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Glossary



ACL

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



adapter card

See host adapter.



aggregate

A manageable unit of RAID-protected storage, consisting of one or two plexes, that can contain one traditional volume or multiple FlexVol volumes.



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 storage system daemon that triggers e-mail messages from the customer site to NetApp, or to another specified e-mail recipient, when there is a potential storage system problem.



CIFS

Common Internet File System. A file-sharing protocol for networked PCs.



client

A computer that shares files on a storage system.



cluster

A pair of storage systems connected so that one storage system can detect when the other is not working and, if so, can serve the failed storage system's data. For more information about managing clusters, see the Cluster Installation and Administration Guide.



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 storage systems are running.



cluster monitor

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



console

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



continuous media scrub

A background process that continuously scans for and scrubs media errors on the storage system disks.



DAFS

Direct Access File System protocol.



degraded mode

The operating mode of a storage system when a disk is missing from a RAID4 array, when one or two disks are missing from a RAID-DP array, or when the batteries on the NVRAM card are low.



disk ID number

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



disk sanitization

A multiple write process for physically obliterating existing data on specified disks in such a manner that the obliterated data is no longer recoverable by known means of data recovery.



disk shelf

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



Ethernet adapter

An Ethernet interface card.



expansion card

See host adapter.



expansion slot

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



GID

Group identification number.



group

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



host adapter (HA)

A SCSI card, an FC-AL card, a network card, a serial adapter card, or a VGA adapter that plugs into a storage system expansion slot.



hot spare disk

A disk installed in the storage system 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 the storage system is 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.



mail host

The client host responsible for sending automatic e-mail to NetApp 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 your hardware and your system configuration.



MultiStore

An optional 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.



NVRAM cache

Nonvolatile RAM in a storage system, 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 storage system's NVRAM cache.



NVRAM mirror

A synchronously updated copy of the contents of the storage system NVRAM (nonvolatile random access memory) 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 a RAID4 disk drive array. In RAID groups using RAID-DP protection, two parity disks store parity and double-parity information. Used to reconstruct data in failed disk blocks or on a failed disk.



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.



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 an array. Storage systems use either RAID Level 4, which stores all parity information on a single disk, or RAID-DP, which stores parity information on two disks.



RAID disk scrubbing

The process in which a 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 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, such as 9a.1.



SCSI ID

The number of a disk drive on a 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

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



system board

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



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.



vFiler

A virtual 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

Expansion card for attaching a VGA terminal as the console.



volume

A file system.



WAFL

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



WebDAV

Web-based Distributed Authoring and Versioning protocol.



workgroup

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



WORM

Write Once Read Many. WORM storage prevents the data it contains from being updated or deleted. For more information about how Data ONTAP provides WORM storage, see the Data Protection Online Recovery and Backup Guide.

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