Glossary

This glossary includes terms and definitions for Network File System (NFS).

The following cross-references are used in this glossary:

See refers the reader from a term to a preferred synonym, or from an acronym or abbreviation to the defined full form.
See also refers the reader to a related or contrasting term.

To view glossaries for other IBM products, go to http://www-306.ibm.com/software/globalization/terminology/

A
access method: A technique for moving data between main storage and input/output devices.
access permission: A group of designations that determine the users who can access a particular file and how the users can access the file.
ACS: See automatic class selection.
address: A unique code or identifier for a register, device, workstation, system, or storage location.
address space: The range of addresses available to a computer program or process. Address space can refer to physical storage, virtual storage, or both.
alias: An alternative name for an integrated catalog facility (ICF) user catalog, a file that is not a Virtual Storage Access Method (VSAM) file, or a member of a partitioned data set (PDS) or a partitioned data set extended (PDSE).
alias entry: The correlation of an alias with the physical entry name of a user catalog or a data set that is not a Virtual Storage Access Method (VSAM) data set.
allocation: The process of temporarily connecting a program to a data set, file, or device.
American Standard Code for Information Interchange (ASCII): A standard code used for information exchange among data processing systems, data communication systems, and associated equipment. ASCII uses a coded character set consisting of 7-bit coded characters. See also Extended Binary Coded Decimal Interchange Code.
APAR: See authorized program analysis report.
APF: See authorized program facility.
API: See application programming interface.
application programming interface (API): An interface that allows an application program that is written in a high-level language to use specific data or functions of the operating system or another program.
ASCII: See American Standard Code for Information Interchange. See also Extended Binary Coded Decimal Interchange Code.
automatic class selection (ACS): A mechanism for assigning storage management subsystem (SMS) classes and storage groups to data sets. The storage administrator is responsible for establishing ACS routines appropriate for an installation's storage requirements.
automatic class selection routine (ACS routine): A procedural set of automatic class selection (ACS) language statements. Based on a set of input variables, the ACS routine generates, for a data set, the name of a predefined storage management subsystem (SMS) class or a list of names of predefined storage groups.
authorized program analysis report (APAR): A request for correction of a defect in a current release of an IBM-supplied program.
authorized program facility (APF): In a z/OS environment, a facility that permits the identification of programs that are authorized to use restricted functions.

B
basic sequential access method (BSAM): An access method for storing or retrieving data blocks in a continuous sequence, using either a sequential access or a direct access device.
BIOD: The caching daemon that caches directory lookups and file data when remote files are accessed from the host.
block: A string of data elements recorded, processed, or transmitted as a unit. The elements can be characters, words, or physical records.
BSAM: See basic sequential access method.
C
CCSID: See coded character set identifier.
CDRA: See Character Data Representation Architecture.
Character Data Representation Architecture (CDRA): An IBM architecture that defines a set of identifiers, resources, services, and conventions to achieve consistent representation, processing, and interchange of graphic character data in heterogeneous environments.
client: A software program or computer that requests services from a server. See also server, host.
client/server: Pertaining to the model of interaction in distributed data processing in which a program on one computer sends a request to a program on another computer and awaits a response. The requesting program is called a client; the answering program is called a server.
coded character set identifier (CCSID): A 16-bit number that includes a specific set of encoding scheme identifiers, character set identifiers, code page identifiers, and other information that uniquely identifies the coded graphic-character representation.
credential: Detailed information, acquired during authentication, that describes the user, any group associations, and other security-related identity attributes. Credentials can be used to perform a multitude of services, such as authorization, auditing, and delegation. For example, the sign-on information (user ID and password) for a user are credentials that allow the user to access an account.
current directory: See working directory.
D
daemon: A program that runs unattended to perform continuous or periodic functions, such as network control.
DASD: See direct access storage device.
DASD volume: A direct access storage device (DASD) space identified by a common label and accessed by a set of related addresses. See also primary storage.
data control block (DCB): A control block used by access method routines in storing and retrieving data.
Data Encryption Standard (DES): A cryptographic algorithm designed to encrypt and decrypt data using a private key.
data set: The major unit of data storage and retrieval, consisting of a collection of data in one of several prescribed arrangements and described by control information to which the system has access. See also file.
data set control block (DSCB): A control block in the volume table of contents (VTOC) that describes data sets.
data set organization (DSORG): The type of arrangement of data in a data set, such as sequential organization or partitioned organization.
DBCS: See double-byte character set.
DCB: See data control block.
DES: See Data Encryption Standard.
DES authentication: A type of encryption algorithm that requires a client to send credentials (name, conversation key, window key, and a time stamp) to the server. The server then returns a verifier to the client. Data Encryption Standard (DES) credentials are sometimes called secure credentials because they are based on a sender's ability to encrypt data using a common time reference; a randomly generated key is required to encrypt a common reference time that is then used to create a conversation key.
DFSMS (Data Facility Storage Management Subsystem): An operating environment that helps automate and centralize the management of storage. To manage storage, the storage management subsystem (SMS) provides the storage administrator with control over data class, storage class, management class, storage group, and automatic class selection (ACS) routine definitions.
DFSMSdfp: A DFSMS functional component and a base element of z/OS that provides functions for storage management, data management, device management, and distributed data access.
direct access: A file access method allowing reading and writing of records in an arbitrary order.
direct access storage device (DASD): A device that allows storage to be directly accessed, such as a disk drive.
direct data set: A data set that has records in random order on a direct access volume. Each record is stored or retrieved according to its actual address or its address relative to the beginning of the data set. See also sequential data set.
directory: In UNIX, a file that maps the names of other directories and files to their locations.
double-byte character set (DBCS): A set of characters in which each character is represented by two bytes. These character sets are commonly used by national languages, such as Japanese and Chinese, that have more symbols than can be represented by a single byte.
DSCB: See data set control block.
E
EBCDIC: See Extended Binary Coded Decimal Interchange Code. See also American Standard Code for Information Interchange.
entry-sequenced data set (ESDS): A data set whose records are loaded without respect to their contents, and whose relative byte addresses cannot change. Records are retrieved and stored by addressed access, and new records are added at the end of the data set.
ESDS: See entry-sequenced data set.
exports data set: In z/OS, an MVS file on the server containing entries for directories that can be exported to Network File System (NFS) clients. It is used by the server to determine which MVS files and prefixes can be mounted by a client, and to write-protect MVS files on the server.
Extended Binary Coded Decimal Interchange Code (EBCDIC): A coded character set of 256 8-bit characters developed for the representation of textual data. See also American Standard Code for Information Interchange.
External Data Representation (XDR): A standard developed by Sun Microsystems, Incorporated to represent data in machine-independent format. Because XDR is a vendor-independent method for representing the data, new computer architectures can be integrated into the network without requiring the updating of translation routines.
F
file: A collection of related data that is stored and retrieved by an assigned name. See also data set.
file handle: A number that is used by the client and server sides of the Network File System (NFS) to specify a particular file or prefix.
file system: The collection of files and file management structures on a physical or logical mass storage device, such as a diskette or minidisk.
File Transfer Protocol (FTP): In the Internet suite of protocols, an application layer protocol that uses TCP and Telnet services to transfer bulk-data files between machines or hosts.
FMID: See function modification identifier.
FTP: See File Transfer Protocol.
function modification identifier (FMID): With SMP/E, a code that identifies the release levels of a program product.
G
gateway: A device or program used to connect networks or systems with different network architectures.
GID: See group ID.
group: With respect to partitioned data sets (PDSs), a member and the member's aliases that exist in a PDS or partitioned data set extended (PDSE), or in an unloaded PDSE.; A collection of users who can share access authorities for protected resources.
group ID (GID): In the UNIX operating system, an integer that uniquely identifies each group of users to the operating system.
H
handle: A character string that represents an object, and is used to retrieve the object.
HFS data set: See hierarchical file system data set.
hierarchical file system data set (HFS data set): A data set that contains a particular type of file system that is compliant with the Portable Operating System Interface (POSIX). An HFS data set is a collection of files and directories organized in a hierarchical structure that can be accessed using z/OS UNIX System Services (z/OS UNIX).
host: A computer that is connected to a network and provides an access point to that network. The host can be a client, a server, or both a client and server simultaneously. See also server, client.
I
IDCAMS: An IBM program that is used to process access method services commands. It can be invoked as a job or jobstep, from a TSO terminal or from within a user's application program.
Interactive System Productivity Facility (ISPF): An IBM licensed program that serves as a full-screen editor and dialog manager. Used for writing application programs, it provides a means of generating standard screen panels and interactive dialogs between the application programmer and terminal user. See also Time Sharing Option.
Internet: The worldwide collection of interconnected networks that use the Internet suite of protocols and permit public access.
Internet Protocol (IP): A protocol that routes data through a network or interconnected networks. This protocol acts as an intermediary between the higher protocol layers and the physical network. See also Transmission Control Protocol.
interprocess communication (IPC): The process by which programs send messages to each other. Sockets, semaphores, signals, and internal message queues are common methods of interprocess communication.
IP: See Internet Protocol. See also Transmission Control Protocol.
IPC: See interprocess communication.
J
JCL: See job control language.
job control language (JCL): A command language that identifies a job to an operating system and describes the job's requirements.
K
key-sequenced data set (KSDS): A VSAM file or data set whose records are loaded in key sequence and controlled by an index.
KSDS: See key-sequenced data set.
L
library: A partitioned data set or a series of concatenated partitioned data sets. See also partitioned data set extended.
local host: The computer to which a user's terminal is directly connected.
M
management class: A user-defined schedule for moving objects from one storage class to the next. Management class describes the retention and class transition characteristics for a group of objects in a storage hierarchy.
master catalog: A key-sequenced data set (KSDS) or file with an index containing extensive data set and volume information that the Virtual Storage Access Method (VSAM) requires to locate data sets or files, allocate and deallocate storage space, verify the authorization of a program or operator to gain access to a data set or file, and accumulate usage statistics for data sets or files.
maximum transmission unit (MTU): The largest possible unit of data that can be sent on a given physical medium in a single frame. For example, the maximum transmission unit for Ethernet is 1500 bytes.
MBCS: See multibyte character set. See also double-byte character set, single-byte character set, Unicode.
mount: To place a data medium in a position to operate.
mount handle data set: In z/OS, a data set used to store the file handles of Network File System (NFS) mount points.
mount point: A directory established in a workstation or a server local directory that is used during the transparent accessing of a remote file.; In Linux operating systems and in UNIX operating systems such as AIX, the directory at which a file system is mounted and under which other file systems may be mounted.
MTU: See maximum transmission unit.
multibyte character set (MBCS): A character set that represents single characters with more than a single byte. See also double-byte character set, single-byte character set, Unicode.
Multiple Virtual Storage (MVS): An IBM operating system that accesses multiple address spaces in virtual storage.
MVS: See Multiple Virtual Storage.
N
network: In data communication, a configuration in which two or more locations are physically connected for the purpose of exchanging data.
Network Lock Manager (NLM): A service used by Network File System (NFS) when using version 2 or 3 of the NFS protocol that allows a client on the host to lock a range of bytes or an entire file on the NFS server.
Network Status Manager (NSM): A service used by Network File System (NFS) when using version 2 or 3 of the NFS protocol to determine whether resources, such as file open share or byte range locks, are still in use by a remote client.
NLM: See Network Lock Manager.
NSM: See Network Status Manager.
null credential: A type of credential that is usually associated with diskless workstations. Because there is no repository of information that is local to the workstation, it is not possible to obtain identifying information.
O
object: A directory or file.
P
partitioned data set (PDS): A data set on direct access storage that is divided into partitions, called members, each of which can contain a program, part of a program, or data. See also sequential data set.
partitioned data set extended (PDSE): A system-managed data set that contains an indexed directory and members that are similar to the directory and members of partitioned data sets (PDSs). See also library.
PDS: See partitioned data set. See also sequential data set.
PDS directory: A set of records in a partitioned data set (PDS) that is used to relate member names to their locations within the data set.
PDSE: See partitioned data set extended. See also library.
permission code: A 3-digit octal code or a nine-letter alphabetic code that indicates the access permission for a UNIX file. The access permissions are read, write, and execute.
permission field: One of the 3-character fields within the permissions column of a UNIX directory listing. The permission field indicates the read, write, and run permissions for the file or directory owner and for the group. It is used by file systems to control access.
PFS: See physical file system.
physical file system (PFS): The part of the operating system that handles the actual storage and manipulation of data on a storage medium.
port: An end point for communication between applications, generally referring to a logical connection. A port provides queues for sending and receiving data. Each port has a port number for identification.
Portable Operating System Interface (POSIX): An IEEE family of standards designed to provide portability between operating systems that are based on UNIX. POSIX describes a wide spectrum of operating-system components ranging from C language and shell interfaces to system administration
Portmapper: A program that maps client programs to the port numbers of server programs. A portmapper is used with remote procedure call (RPC) programs. Portmapper does not support IPv6. RPCBIND is required for IPv6. See also RPCBIND.
port number: The part of a socket address that identifies a port within a host.
POSIX: See Portable Operating System Interface.
primary storage: A direct access storage device (DASD) volume available to users for data allocation. The volumes in primary storage are called primary volumes.
primary volume: A volume managed by DFSMShsm containing data sets that are directly accessible to the user. See also primary storage.
program temporary fix (PTF): For System i, System p, and System z products, a fix that is tested by IBM and is made available to all customers.
protocol: A set of rules controlling the communication and transfer of data between two or more devices or systems in a communication network.
PTF: See program temporary fix.
Q
QSAM: See queued sequential access method.
queued sequential access method (QSAM): An access method for storing and retrieving logical records in a continuous sequence. Input data blocks awaiting processing or output data blocks awaiting transfer to auxiliary storage are queued on the system to minimize delays in I/O operations.
R
RACF: See Resource Access Control Facility.
relative record data set (RRDS): A type of Virtual Storage Access Method (VSAM) data set whose records have fixed or variable lengths, and are accessed by relative record number.
Remote Procedure Call (RPC): A protocol that allows a program on a client computer to run a program on a server.
Resource Access Control Facility (RACF): An IBM licensed program that provides access control by identifying users to the system; verifying users of the system; authorizing access to protected resources; logging unauthorized attempts to enter the system; and logging accesses to protected resources.
Resource Measurement Facility (RMF): A feature of z/OS that measures selected areas of system activity and presents the data collected in the format of printed reports, System Management Facility (SMF) records, or display reports.
RMF: See Resource Measurement Facility.
root: The UNIX definition for a directory that is the base for all other directories.; The user name for the system user with the most authority.
root user: A system user who operates without restrictions. A root user has the special rights and privileges needed to perform administrative tasks.
RPC: See Remote Procedure Call.
RPCBIND: A program that maps client programs to the port numbers of server programs. RPCBIND is used with remote procedure call (RPC) programs. RPCBIND is required for IPv6. See also Portmapper.
RRDS: See relative record data set.
S
SAF: See System Authorization Facility.
SDSF: See System Display and Search Facility.
sequential file: A type of MVS file that has its records stored and retrieved according to their physical order within the file. It must be on a direct access volume.
sequential data set: A data set whose records are organized on the basis of their successive physical positions, such as on magnetic tape. See also partitioned data set, direct data set.
server: A software program or a computer that provides services to other software programs or other computers. See also host, client.
sharing: Using a file on a remote system. Sharing is performed by mounting the remote file system and then reading or writing files in that remote system.
single-byte character set (SBCS): A coded character set in which each character is represented by a 1-byte code. A 1-byte code point allows representation of up to 256 characters. See also double-byte character set.
SMF: See System Management Facilities.
SMP/E: See SMP/E for z/OS.
SMP/E for z/OS: An IBM licensed program used to install software and software changes on z/OS systems.
SMS: See storage management subsystem (SMS).
stale file handle: A file handle for a file or prefix that is no longer valid.
stateless: Having no record of previous interactions. A stateless server processes requests based solely on information provided with the request itself, and not based on memory from earlier requests.
storage management subsystem (SMS): Software that automates as much as possible the management of physical storage by centralizing control, automating tasks, and providing interactive controls for system administrators.
superuser: See root user.
System Management Facilities (SMF): A component of z/OS that collects and records a variety of system and job-related information.
System Authorization Facility (SAF): An MVS interface with which programs can communicate with an external security manager, such as RACF.
System Display and Search Facility (SDSF): An IBM-licensed program that provides a menu-driven full-screen interface that is used to obtained detailed information about jobs and resources in a system.
system-managed storage: Storage managed by the storage management subsystem (SMS). System-managed storage attempts to deliver required services for availability, performance, space, and security to applications.
T
TCP/IP: See Transmission Control Protocol/Internet Protocol.
Time Sharing Option (TSO): A base element of the z/OS operating system with which users can interactively work with the system. See also Interactive System Productivity Facility.
Time Sharing Option Extensions (TSO/E): A licensed program that is based on Time Sharing Option (TSO). With TSO/E, MVS users can interactively share computer time and resources.
Transmission Control Protocol (TCP): A communication protocol used in the Internet and in any network that follows the Internet Engineering Task Force (IETF) standards for internetwork protocol. TCP provides a reliable host-to-host protocol in packet-switched communication networks and in interconnected systems of such networks. See also Internet Protocol.
Transmission Control Protocol/Internet Protocol (TCP/IP): An industry-standard, nonproprietary set of communication protocols that provides reliable end-to-end connections between applications over interconnected networks of different types.
TSO: See Time Sharing Option. See also Interactive System Productivity Facility.
TSO/E: See Time Sharing Option Extensions.
U
UDP: See User Datagram Protocol.
UID: See user identification.
Unicode: A character encoding standard that supports the interchange, processing, and display of text that is written in the common languages around the world, plus some classical and historical texts. The Unicode standard has a 16-bit character set defined by ISO 10646.
UNIX: A highly portable operating system that features multiprogramming in a multiuser environment. The UNIX operating system was originally developed for use on minicomputers, but was adapted for mainframes and microcomputers. The AIX operating system is IBM's implementation of the UNIX operating system.
UNIX authentication: The process of identifying a client process, which requires that the client process send credentials to the server.
user catalog: An optional catalog used in the same way as the master catalog and pointed to by the master catalog. Employing a user catalog lessens the contention for the master catalog and facilitates volume portability.
User Datagram Protocol (UDP): An Internet protocol that provides unreliable, connectionless datagram service. It enables an application program on one machine or process to send a datagram to an application program on another machine or process.
user ID: See user identification.
user identification (user ID): The name used to associate the user profile with a user when a user signs on to a system.
V
Virtual Storage Access Method (VSAM): An access method for direct or sequential processing of fixed-length and variable-length records on disk devices. The records in a VSAM data set or file can be organized in logical sequence by a key field (key sequence), in the physical sequence in which they are written on the data set or file (entry sequence), or by relative-record number.
volume: A discrete unit of storage on disk, tape or other data recording medium that supports some form of identifier and parameter list, such as a volume label or input/output control.
VSAM: See Virtual Storage Access Method.
W
working directory: The active directory. When a file name is specified without a directory, the current directory is searched.
X
XDR: See External Data Representation.
Z
zFS: See z/OS file system.
z/OS: An operating system for the IBM z Series product line that uses 64-bit real storage.
z/OS file system (zFS): A type of file system that resides in a Virtual Storage Access Method (VSAM) linear data set (LDS).