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.
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).
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.
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 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.
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 buses, networks are typically characterized by large numbers of nodes that act as peers, large inter-node separation, and flexible configurability. See channel, I/O bus, 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 elements that connect to a network and provide file access services to computer systems.
These elements 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 http://www.ndmp.org.
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.
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 bus 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 bus addresses or on a different host I/O bus. 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 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-volatility
[Storage System] A property that data will be preserved, even if normal environmental conditions are not met, such as on disks or tapes, which continue to preserve the data on them when electrical power is cut.
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.
NUMA
[Computer System] Shorthand for Non-Uniform Memory Architecture.
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.
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.
N_Port_ID Virtualization (NPIV)
[Fibre Channel] The ability for a single physical Fibre Channel end point (N_Port) to support multiple, uniquely addressable, logical end points.
Protocols that support NPIV are defined in ANSI INCITS T11 Fibre Channel standards, including FC-FS-2 and FC-SW-4.
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. See FC-GS-5.
2. [Network] A server, such as a DNS server, that resolves textual names to machine addresses and vice versa.
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).
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.
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 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. The Nx_Port physically attached to the local fabric.
NDMP
[Management] [Network] Acronym for Network Data Management Protocol.
nearline data
[Data management] Deprecated synonym for near-online data.
The term is deprecated because of trademark issues.
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.
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 buses, networks are typically characterized by large numbers of nodes that act as peers, large inter-node separation, and flexible configurability. See channel, I/O bus, 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 elements that connect to a network and provide file access services to computer systems.
These elements 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 is undertaking work in this area, based on donation of the original code from http://www.ndmp.org to the SNIA by NetApp and EMC.
Network File System (protocol) (NFS)
[File System] [Standards] A distributed file system and its associated network protocol commonly implemented in UNIX systems.
Most other computer systems have also implemented NFS clients and/or servers. The IETF is responsible for the NFS standard.
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.
NFS
[File System] [Standards] Acronym for Network File System.
NIC
[Network] Acronym for Network Interface Card.
NIST
[Data Security] Acronym for National Institute of Standards and Technology.
NL_Port
[Fibre Channel] A “Node Loop” port, capable of arbitrated loop functions and protocols.
An NL_Port connects via an arbitrated loop to other NL_Ports and at most a single FL_Port. NL_Ports handle creation, detection, and flow of message units to and from the connected systems. NL_Ports are end ports in virtual point-to-point links through a fabric, for example the NL_Port on an end node to FL_Port on a switch to the F_Port in that switch to the N_Port on the other end node using a single Fibre Channel fabric switch. In the absence of a fabric switch FL_Port, NL_Ports can communicate with other NL_Ports in virtual point-to-point links through a FC_AL open loop circuit often through FC_AL (Arbitrated Loop) hub or loop switch devices.
node
[Network] [Storage System] An addressable entity connected to an I/O bus 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.
For example, a controller failover in a redundant disk subsystem is non-transparent if the surviving controller exports the other’s virtual disks at different host I/O bus addresses or on a different host I/O bus, requiring hosts to remount LUNs or filesystems. 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 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-volatility
[Storage System] A property that data will be preserved, even if normal environmental conditions are not met, such as on disks or tapes, which continue to preserve the data on them when electrical power is cut.
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.
NUMA
[Computer System] Acronym for Non-Uniform Memory Architecture.
NVRAM
[Computer System] Acronym 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.
