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. See expansion card.
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 the system. The setup program automatically configures the 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 e-mail messages. At any time after you run the setup program, you can configure the system to work with other clients in the same way it does with the administration host.
aggregate: A manageable unit of RAID-protected storage, consisting of one or two plexes, that can contain one traditional volume or multiple FlexVol volumes. For more information about aggregates, see the Data ONTAP Storage Management Guide.
API: Application Programming Interface. A software toolkit designed to provide system access to external programs. Data ONTAP provides an API called Manage ONTAP.
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 system’s domain, or by the system itself, using its /etc/passwd file.
AutoSupport: A system daemon that triggers messages from the customer site to NetApp or another specified e-mail recipient when there is a potential 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.
CLI: Command Line Interface. The Data ONTAP system prompt is an example of a Command Line Interface.
client: A computer that shares files on a storage system.
active/active pair: 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 data. When storage systems are in an active/active configuration, each system is also referred to as a node.
active/active configuration interconnect: Cables and adapters with which the two storage systems in an active/active configuration are connected and over which heartbeat and WAFL log information are transmitted when both systems are running.
active/active configuration monitor: Software that administers the relationship of storage systems in the active/active configuration 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.
continuous media scrub: A background process that continuously scans for and scrubs media errors on the storage system disks.
copy-on-write: The technique for creating Snapshot copies without consuming excess disk space.
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.
emulated storage system: A software copy of a failed storage system that is hosted by its takeover storage system. The emulated storage system appears to users and administrators to be 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. See adapter card.
expansion slot: The slots on the storage system board into which you insert expansion cards.
failed storage system: A physical storage system that has ceased operating. In an active/active configuration, it remains the failed storage system until a 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.
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 storage system to the other that indicates that the storage system is in operation. Heartbeat information is also stored on disk.
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.
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 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 storage system that is used to store the active/active configuration state information of a storage system. If that 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.
maintenance mode: An option when booting a storage system from a system boot disk. Maintenance mode provides special commands for troubleshooting hardware and 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.
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 ATM adapter card.
normal mode: The state of a storage system when there is no takeover in the active/active configuration.
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) 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 a RAID4 disk drive array. In RAID groups using RAID-DP protection, two parity disks store the parity and double-parity information. Used to reconstruct data in failed disk blocks or on a failed disk.
partner: From the point of view of a local storage system, the other storage system in an active/active configuration.
partner mode: The method you use to communicate through the command-line interface with a virtual storage system during a takeover.
POST: Power-on self-tests. The tests run by a storage system after the power is turned on.
qtree: A special subdirectory of the root of a volume that acts as a virtual subvolume with special attributes. For more information about qtrees, see the Data ONTAP Storage Management Guide.
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 all 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 used by the Windows operating system.
Snapshot copy: An online, read-only copy of an 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 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.
takeover: The emulation of the failed node identity by the takeover node in an active/active configuration; the opposite 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 node disk shelves and network connections. The takeover node maintains its own identity and the virtual node maintains the failed node 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.
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.
volume: A file system. For more information about volumes, see the Data ONTAP Storage Management Guide.
WAFL: Write Anywhere File Layout. The WAFL file system was designed for the storage system 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.