Online SNIA Dictionary

An identifier associated with a removable media or cartridge.

Labels may be humanly readable, machine readable, or both. See external volume serial number, media ID.

laboratory attack [Permalink]

Use of sophisticated signal recovery equipment in a laboratory environment to recover information from data storage media. [NIST SP 800-88]

Magnetic force microscopes and other similar equipment can be used to recover data from magnetic media that has been erased or damaged.

LAN [Permalink]

Acronym for Local Area Network.

LAN-free backup [Permalink]

A backup methodology that moves data without using LAN resources.

Data may be moved over a SAN or via direct attached storage.

lane [Permalink]

One of multiple point-to-point physical connections that make up a single link.

latency [Permalink]

A time period between two events.

Synonym for I/O request execution time, the time between the making of an I/O request and completion of the request's execution.

Short for rotational latency, the time between the completion of a seek and the instant of arrival of the first block of data to be transferred at the disk's read/write head.

latent fault [Permalink]

A failure of a system component that has not been observed because the failed aspect of the component has not been exercised since the occurrence of the failure.

A media defect on a disk surface is a latent fault until an attempt is made to read the data in a block that spans the defect.

LBA [Permalink]

Acronym for Logical Block Address.

LC [Permalink]

An optical fiber connector complying with international standard IEC 61754-20.

LC connectors are the most common connector in optical data communications networks, including Ethernet and Fibre Channel. A dual LC connector is used, carrying separate fibers for transmitted and received data.

LDAP [Permalink]

Acronym for Lightweight Directory Access Protocol.

LDM [Permalink]

Acronym for Logical Disk Manager.

least privilege [Permalink]

The security objective of granting users only those accesses they need to perform their official duties. [NIST SP 800-12]

LED [Permalink]

Acronym for light emitting diode.

legal hold [Permalink]

Process of suspending the normal disposition or processing of records and Electronically Stored Information as a result of current or anticipated litigation, audit, government investigation or other such matters. [ISO/IEC 27050-1]

The issued communication that implements the legal hold can also be called a "hold," "preservation order," "suspension order," "freeze notice," "hold order," or "hold notice."

library [Permalink]

A storage device containing a robotic media handler capable of storing multiple pieces of removable media and loading and unloading them from one or more drives in arbitrary order.

See also virtual tape library.

lifecycle deletion [Permalink]

The deletion of data at the end of its lifecycle.

See disposition policy.

light emitting diode [Permalink]

A multimode light source based on optical diodes.

Lightweight Directory Access Protocol [Permalink]

An IETF protocol for creating, accessing and removing objects and data from a directory.

LDAP, originally a subset of the X.500 protocol, provides the ability to search, compare, add, delete and modify directory objects, as well as modifying the names of these objects.

Linear Tape File System [Permalink]

1. [File System] A self-describing, self-contained tape storage format intended for interchange of data between different software systems.

See ISO/IEC 20919.

2. [File System] A software or hardware implementation of a file system using the LTFS format.

Linear Tape Open [Permalink]

An open standard magnetic tape technology developed in cooperation by HP, IBM and Quantum.

link [Permalink]

1. [Network] A physical connection (electrical or optical) between two nodes of a network.

2. [Network] Two unidirectional fibers or conductors transmitting in opposite directions and their associated transmitters and receivers.

3. [Network] A collection of multiple lanes.

4. [Fibre Channel] The full-duplex FC-0 level association between FC-1 entities in directly attached ports.

5. [Fibre Channel] The point-to-point physical connection from one element of a Fibre Channel fabric to the next.

LIP [Permalink]

Acronym for Loop Initialization Primitive.

LISM [Permalink]

Acronym for Loop Initialization Select Master.

litigation hold [Permalink]

Synonym for legal hold.

load balancing [Permalink]

The adjustment of system and/or application components and data so that work is spread as evenly as possible across a system's physical resources.

Load balancing may be done manually (by a human) or automatically (by some means that does not require human intervention). See load optimization, load sharing.

load generator [Permalink]

Hardware and software environment executing the workload generator to drive the system under evaluation.

load optimization [Permalink]

The manipulation of an I/O load in such a way that performance is optimal by some objective metric.

Load optimization may be achieved by load balancing across several components, or by other means, such as request reordering or interleaved execution. See load balancing, load sharing.

load sharing [Permalink]

The division of a task among several components, without any attempt to equalize each component's share of the work.

See I/O load balancing, load optimization.

load/store architecture [Permalink]

A CPU architecture in which memory is only accessed through load and store instructions, and all other instructions access data in registers only.

load/store operations [Permalink]

Operations that move data between CPU registers and memory.

local area network [Permalink]

A communications infrastructure, typically Ethernet, designed to connect intercommunicating nodes over a limited distance.

See wide area network.

Local Area Network Emulation (LANE) [Permalink]

A collection of protocols and services that combine to create an emulated local area network using ATM as the underlying network.

Local area network emulation (LANE) enables intelligent devices with ATM connections to communicate with remote LAN-connected devices as if they were directly connected to the LAN.

local backup [Permalink]

A backup methodology that utilizes host resources to copy data to a backup location that is accessible to the same host.

See LAN-free backup.

local F_Port [Permalink]

The F_Port to which a particular N_Port is directly attached by a link.

locking [Permalink]

Any method of managing concurrent access to a resource.

logical block [Permalink]

A block of data stored on a storage device, and associated with an address for purposes of retrieval or overwriting.

The term logical block is typically used to refer to the host's view of data addressing on a physical device. Within a storage device, there is often a further conversion between the logical block addresses presented to hosts and the physical media locations at which the corresponding data is stored. See physical block, virtual block.

logical block address [Permalink]

The address of a logical block.

Logical block addresses are typically used in hosts' I/O commands. The SCSI block command protocol, for example, uses logical block addresses.

logical disk [Permalink]

A deprecated synonym for virtual disk.

logical disk manager [Permalink]

A name for the volume management control software used by Microsoft Windows.

logical unit [Permalink]

The addressable entity within a SCSI target that executes I/O commands.

logical unit number [Permalink]

[SCSI] The SCSI identifier of a logical unit within a target.
[Storage System] The address for a logical unit.

logical volume [Permalink]

A synonym for virtual disk.

long wavelength laser [Permalink]

A laser with a wavelength of 1300 nm or longer.

A long wavelength laser usually has a wavelength of 1300 or 1550 nanometers.

long-term data retention [Permalink]

The practice of storing data for an extended period of time.

In order to achieve long-term data retention, issues related to security, media, and data formats must be addressed. See data preservation.

long-term preservation [Permalink]

The act of maintaining information, in a correct and independently understandable form, over a period of decades or longer.

See digital preservation.

loop initialization [Permalink]

The process by which a Fibre Channel Arbitrated Loop network initializes upon power up or recovers after a failure or other unexpected condition.

Loop Initialization Primitive (LIP) [Permalink]

A Fibre Channel Arbitrated Loop primitive used to (1) initiate a process that results in unique addressing for all nodes, (2) indicate a loop failure, or (3) reset a specific node.

loop port state machine [Permalink]

Logic that monitors and performs the tasks required for initialization and access to a Fibre Channel Arbitrated Loop.

loopback [Permalink]

An operational mode where transmitted data is directed back to the local receiver.

lossless Ethernet bridging element [Permalink]

An Ethernet bridging function supporting lossless Ethernet MACs.

lossless Ethernet MAC [Permalink]

A full duplex Ethernet MAC that supports at least 2.5KB jumbo frames and implements extensions to avoid Ethernet frame loss due to congestion (e.g., the Ethernet Pause mechanism).

lossless Ethernet network [Permalink]

An Ethernet network composed only of full duplex links, Lossless Ethernet MACs, and Lossless Ethernet bridging elements.

LTFS [Permalink]

Acronym for Linear Tape File System.

LTFS Index [Permalink]

Metadata which describes the file data types and locations on an LTFS volume.

LTFS Volume [Permalink]

A tape cartridge utilizing the LTFS format.

LTO [Permalink]

Acronym for Linear Tape Open.

LU [Permalink]

Acronym for logical unit.