N

N_Port

[Fibre Channel] A “Node” port that connects via a point-to-point link to either a single N_Port or a single F_Port.

N_Ports handle creation, detection, and flow of message units to and from the connected systems. N_Ports are end ports in virtual point-to-point links through a fabric, for example the N_Port on an end node to F_Port on a switch to F_Port in that switch to the N_Port on the other end node using a single Fibre Channel fabric switch. An N_Port is assumed to always refer to an Nx_Port in a direct Fabric-attached PN_Port, and does not include NL_Ports

N_Port_ID Virtualization (NPIV)

[Fibre Channel] The ability for a single physical Fibre Channel node or switch to support more than one Nx_Port on a single point-to-point link.

N_Port_Name

[Fibre Channel] A Name_Identifier associated with an N_Port.

NAA

[Network] [Standards] Acronym for Network Address Authority.

Name_Identifier

[Fibre Channel] A 64-bit identifier, with a 60-bit value preceded by a 4-bit Network_Address_Authority Identifier, used to identify entities in Fibre Channel (e.g., Nx_Port, node, F_Port, or Fabric).

name server

1. [Fibre Channel] A distributed service provided by the fabric to register and discover the attributes of Fibre Channel N_Ports.

Once registered, the attributes may be viewed by requesting N_ports.

2. [Network] A server, such as a DNS server, that resolves textual names to machine addresses and vice versa.

namespace

1. [File System] The set of valid names recognized by a file system.

2. [General] In XML, a document at a specific Web address (URL) that lists the names of data elements and attributes that are used in other XML files.

3. [Management] In CIM and WBEM, a collection of object definitions and instances that are logically consistent.

naming

[Computer System] The mapping of address space to a set of objects.

Naming is typically used either for human convenience (e.g., symbolic names attached to files or storage devices), or to establish a level of independence between two system components (e.g., identification of files by inode names or identification of computers by IP addresses).

NAS

[Network] [Storage System] Acronym for Network Attached Storage.

National Institute of Standards and Technology (NIST)

[Standards] [Data Security] A non-regulatory federal agency within the U.S. Commerce Department's Technology Administration.

NIST's mission is to develop and promote measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. Specifically, the Computer Security Division within NIST's Information Technology Laboratory managed the Advanced Encryption Standard (AES) program.

native data format

[Legal] The original, non-derived format and structure of data, together with its associated metadata.

Where data is unstructured, native file format means the original format of a file. While structured or unstructured data may be read by other programs, native data format means data whose state and integrity are unchanged since generation by its instantiating application.

Native Fabric

[Fibre Channel] In inter-fabric routing (IFR), the local fabric where the Native Nx_Port resides.

Native Nx_Port

[Fibre Channel] A role of an Nx_Port in an IFR environment.

A Native Nx_Port is physically attached to the local fabric.

NDMP

[Management] [Network] Acronym for Network Data Management Protocol.

near-online data

[Data Management] Data that is accessible within some moderate length of time, usually some number of seconds.

See active data, offline data.

near-online storage

[Energy] Storage systems with first data access times > 80 ms and less than several seconds, as specified in the SNIA Emerald™ Power Efficiency Measurement Specification.

network

[Network] An interconnect that enables communication among a collection of attached nodes, consisting of optical or electrical transmission media, infrastructure in the form of hubs and/or switches, and protocols that make message sequences meaningful.

In comparison to I/O interconnects, networks are typically characterized by large numbers of nodes that act as peers, large inter-node separation, and flexible configurability. See channel, I/O interconnect, local area network, storage area network.

network adapter

[Network] An adapter that connects an intelligent device to a network, also called a network interface card, or NIC.

See Ethernet adapter, NIC.

Network Address Authority (NAA)

[Fibre Channel] A 4-bit field used to identify the controlling authority for guaranteeing uniqueness of World Wide Names (WWNs).

In a Fibre Channel environment, several Naming Authorities can be active at the same time, therefore Fibre Channel prepends the NAA field to World Wide Names to guarantee global uniqueness. An NAA =1, for example, indicates IEEE 48-bit Identifiers. The NAA also identifies one of several WWN formats, for example Format 1, Format 2 and Format 5.

Network Attached Storage (NAS)

1. [Storage System] A term used to refer to storage devices that connect to a network and provide file access services to computer systems.

These devices generally consist of an engine that implements the file services, and one or more devices, on which data is stored.

2. [Network] A class of systems that provide file services to host computers using file access protocols such as NFS or CIFS.

See storage area network.

network backup

[Data Recovery] A backup methodology that copies data over a LAN to a Backup Server.

Network Data Management Protocol (NDMP)

[Data Recovery] A communications protocol that allows data storage devices, robotic library devices, and backup applications to intercommunicate for the purpose of performing backups.

NDMP is an open standard protocol for network-based backup of NAS devices. It allows a network backup application to control the retrieval of data from, and backup of, a server without third-party software. The control and data transfer components of backup and restore are separated. NDMP is intended to support tape drives, but can be extended to address other devices and media in the future. The SNIA has developed a v4 reference implementation, based on donation to it of the original code from NetApp and PDC.

Network File System (protocol) (NFS)

[File System] [Standards] A distributed file system and its associated network protocol, commonly implemented in UNIX systems.

The IETF maintains the NFS standard. NFS clients and/or servers are available for all major platforms at this point.

Network Interface Card (NIC)

[Network] An I/O adapter that connects a computer or other type of node to a network.

A NIC is commonly a plug-in circuit board, however, the term is also used to denote an ASIC or set of ASICs on a computer system board that perform the network I/O adapter function. The term NIC is universally used in Ethernet and token ring contexts. In Fibre Channel contexts, the terms host bus adapter, HBA and adapter are used in preference to NIC. See host bus adapter, I/O adapter.

nexus

[SCSI] A temporary relationship between two SCSI devices, consisting of at least a target identifier and initiator identifier.

A full working nexus, known as an I_T_L_Q nexus, also contains a Logical Unit Number (LUN) and a Queue tag.

NFS

[File System] [Standards] Acronym for Network File System.

NIC

[Network] Acronym for Network Interface Card.

NIST

[Data Security] Shorthand for National Institute of Standards and Technology.

NL_Port

[Fibre Channel] A “Node Loop” port, i.e., an Nx_Port that is communicating via an Arbitrated Loop.

NL_Ports are end points for Fibre Channel communication via Arbitrated Loop topologies that are attached to a Fabric, for example NL_Port to FL_Port to F_Port to N_Port using a single Fibre Channel Fabric switch. See F_Port, FL_Port, Nx_Port, L_Port.

node

[Network] [Storage System] An addressable entity connected to an I/O interconnect or network.

The term node is used to refer to computers, storage devices, storage subsystems and network interconnection devices such as switches, routers and gateways. The component of a node that connects to the bus or network is a port.

Node_Name

[Fibre Channel] A Name_Identifier that is associated with a Fibre Channel node.

non-erasable content

[Data Management] Content that cannot be deleted except in accordance with a retention policy.

non-linear mapping

[Storage System] Any form of tabular mapping in which there is not a fixed size correspondence between the two mapped address spaces.

Non-linear mapping is required in disk arrays that compress data, since the space required to store a given range of virtual blocks depends on the degree to which the contents of those blocks can be compressed, and therefore changes as block contents change. See algorithmic mapping, dynamic mapping, tabular mapping.

nonrepudiation

[Data Security] Assurance that a subject cannot later deny having performed some action.

For communication, this may involve providing the sender of data with proof of delivery and the recipient with proof of the sender's identity, so neither can later deny having participated in the communication. Digital signatures are often used as a non-repudiation mechanism for stored information in combination with timestamps.

non-transparent failover

[Computer System] A failover from one component of a redundant system to another that is visible to the external environment.

An example is a controller failover in a redundant disk subsystem if the surviving controller exports the other’s virtual disks at different host I/O interconnect addresses or on a different host I/O interconnect. See transparent failover.

Non-Uniform Memory Architecture (NUMA)

[Computer System] A computer architecture that enables memory to be shared by multiple processors, but with different processors having different access speeds to different parts of the memory.

non-volatile cache

[Storage System] A cache that retains data through power cycles.

non-volatile memory (NVM)

[Computer System] Synonym for NVRAM.

Non-Volatile Random Access Memory (NVRAM)

[Computer System] Computer system random access memory that has been made impervious to data loss due to power failure through the use of UPS, batteries, or implementation technology such as flash memory.

Non-Volatile Dual Inline Memory Module (NVDIMM)

[Hardware] A dual inline memory module that operates as standard RAM while also having persistence across power cycles.

non-volatility

[Storage System] The property of an electronic device that data is preserved even when electrical power is removed.

normal operation
normal mode

[Computer System] A state of a system in which the system is functioning within its prescribed operational bounds.

For example, a disk array subsystem is operating in normal mode when all disks are up, no extraordinary actions (e.g., reconstruction) are being performed, and environmental conditions are within operational range. Sometimes called optimal mode.

not operational (receiver, transmitter)

[Fibre Channel] A receiver or transmitter that is not capable of receiving or transmitting an encoded bit stream based on rules defined by FC-FS-2 for error control.

NPIV

[Fibre Channel] Acronym for N_Port_ID Virtualization.

NQN

[NVMe] Shorthand for NVMe Qualified Name.

NUMA

[Computer System] Shorthand for Non-Uniform Memory Architecture.

NVDIMM

[Hardware] Acronym for Non-Volatile Dual Inline Memory Module.

NVDIMM-F

[Hardware] A dual in-line memory module that is accessed using a block access protocol.

This appears in a separate address space from DRAM and may provide different performance than DRAM.

NVDIMM-N

[Hardware] A dual in-line memory module that operates as persistent DRAM.

The DRAM access methods are either byte- or block-oriented. This may not provide the same performance as volatile DRAM.

NVDIMM-P

[Hardware] A dual in-line memory module that operates as persistent DRAM (NVDIMM–N) and also as a block-accessed drive (NVDIMM–F) using non-volatile memory media.

NVM

[Computer System] Shorthand for non-volatile memory.

NVM Express (NVMe)

[Storage System] A host controller interface with a register interface and command set designed for PCI Express®-based SSDs.

NVM Express over Fibre Channel (NVMeoFC)

[Fibre Channel] Protocol defined by FC-NVMe.

NVM Subsystem

[NVMe] An integrated collection of one or more NVMe controllers and one or more ports.

NVMe

[NVMe] An acronym for NVM Express.

NVMe_DATA IUs

[Fibre channel] The NVMeoFC Information Unit for data frame(s) transfers.

NVMe-oF

[NVMe] Shorthand for NVMe over Fabrics.

NVMe_Port

[Fibre Channel] Nx_Port that supports the FC-NVMe standard.

NVMe command

[Fibre Channel] A command issued by an NVMe host to a controller.

NVMe Completion Queue (CQ)

[NVMe] a circular buffer used to post status for completed NVMe commands

NVMe host

[NVMe] An entity that submits NVMe commands to a controller for processing and receives NVMe command completions from the same controller.

NVMe host port

[Fibre Channel] VN_Port that acts as an interface between an NVMe host and an NVMe-oF fabric.

NVMe over fabrics (NVMe-oF)

[NVMe] An interface to support message-based NVMe operations over a network fabric.

Example network fabrics include Ethernet, Fibre Channel, and InfiniBand.

NVMe Submission Queue (SQ)

[NVMe] a circular buffer that NVMe host software uses to submit commands for processing by the NVMe controller

NVMeoFC

[Fibre Channel] Shorthand for NVM Express over Fibre Channel.

NVMeoFC association

[Fibre Channel] An NVMeoFC layer abstraction for an exclusive communication relationship between a particular NVMe host, connected via a particular initiator NVMe_Port, and a particular controller in an NVM subsystem connected via a particular target NVMe_Port.

NVMeoFC connection

[Fibre Channel] An NVMeoFC layer abstraction representing an NVMe Submission Queue and NVMe Completion Queue pair for an NVMe controller.

NVMeoFC I/O operation

[Fibre Channel] A Fibre Channel exchange that is uniquely associated with an NVMe command.

NVMeoFC port

[Fibre Channel] An NVMe_Port connecting one or more NVMe hosts or NVM subsystems to an FC Fabric.

NVRAM

[Computer System] Shorthand for Non-Volatile Random Access Memory.

NVRAM cache

[Storage System] A quantity of NVRAM used as a cache.

NVRAM cache is particularly useful in RAID array subsystems, filers, database servers, and other intelligent devices that must keep track of the state of multi-step I/O operations even if power fails during the execution of the steps. It also allows arrays to reply to writes before they are committed to disk, as the NVRAM becomes the non-volatile store for the writes.

NVRAM card

[Computer System] A printed circuit module containing NVRAM.

Nx_Port

[Fibre Channel] An end point for Fibre Channel frame communication, having a distinct address identifier and Name_Identifier, providing an independent set of Fibre Channel functions to applications, and having the ability to act as an Originator, a Responder, or both, for Exchanges and Sequences.