Storage Technology Definitions

This glossary explains the meaning of key words and phrases that information technology (IT) and business professionals use when discussing storage and related software products. You can find additional definitions by visiting WhatIs.com or using the search box below.

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  • H

    hybrid cloud storage

    Hybrid cloud storage is an approach to managing cloud storage that uses both local and off-site resources.

  • hybrid flash array

    A hybrid flash array is a solid-state storage system that contains a mix of flash memory drives and hard disk drives.

  • hybrid hard drive (HHD)

    A hybrid hard drive (HHD), sometimes known as a solid-state hybrid drive (SSHD), is a mass storage device that combines a conventional hard disk drive (HDD) and a NAND flash memory module.

  • I

    IDE (Integrated Drive Electronics)

    IDE (Integrated Drive Electronics) is an electronic interface standard that defines the connection between a bus on a computer's motherboard and the computer's disk storage devices.

  • InfiniBand

    InfiniBand is an industry standard communications specification the InfiniBand Trade Association (IBTA) developed.

  • information lifecycle management (ILM)

    Information lifecycle management (ILM) is a comprehensive approach to managing an organization's data and associated metadata, starting with its creation and acquisition through when it becomes obsolete and is deleted.

  • IOPS (input/output operations per second)

    IOPS (input/output operations per second) is the standard unit of measurement for the maximum number of reads/writes to noncontiguous storage locations.

  • iSCSI (Internet Small Computer System Interface)

    ISCSI is a transport layer protocol that describes how Small Computer System Interface (SCSI) packets should be transported over a TCP/IP network.

  • iSCSI initiator

    An Internet Small Computer System Interface initiator is software or hardware that lets a host computer send data to an external iSCSI-based storage array through an Ethernet network adapter over a TCP-based IP network.

  • J

    JBOD (just a bunch of disks)

    JBOD, which stands for 'just a bunch of disks,' is a type of multilevel configuration for disks.

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

  • K

    kibi, mebi, gibi, tebi, pebi and exbi

    Kibi, mebi, gibi, tebi, pebi and exbi are binary prefix multipliers that, in 1998, were approved as a standard by the International Electrotechnical Commission (IEC).

  • Kilo, mega, giga, tera, peta, exa, zetta and all that

    Kilo, mega, giga, tera, peta, exa and zetta are among the binary prefixes used to denote the quantity of something, such as a byte or bit in computing and telecommunications.

  • kilobyte (KB or Kbyte)

    A kilobyte (KB or Kbyte) is a unit of measurement for computer memory or data storage.

  • L

    litigation hold (legal hold, preservation order or hold order)

    A litigation hold -- also known as legal hold, preservation order or hold order -- is an internal process that an organization undergoes to preserve all data that might relate to a legal action involving the organization.

  • logical unit number (LUN)

    A logical unit number (LUN) is a unique identifier for designating an individual or collection of physical or virtual storage devices that execute input/output (I/O) commands with a host computer, as defined by the Small Computer System Interface (SCSI) standard.

  • LUN masking

    LUN masking is an authorization mechanism used in storage area networks (SANs) to make LUNs available to some hosts but unavailable to other hosts.

  • M

    M.2 SSD

    An M.2 SSD is a small form factor solid-state drive (SSD) that internally mounted storage expansion cards use.

  • mebibyte (MiB)

    A mebibyte (MiB) is a unit of measurement used in computer data storage.

  • megabyte (MB)

    A megabyte is a unit of data capacity that is equal to 1,000,000 bytes in decimal notation (base 10) or 1,048,576 bytes in binary notation (base 2).

  • megabytes per second (MBps)

    Megabytes per second (MBps) is a unit of measurement for data transfer speed to and from a computer storage device.

  • mirror site

    A mirror site is a website or set of files on a computer server that has been copied to another computer server so that the site or files are available from more than one place.

  • MRAM (magnetoresistive random access memory)

    MRAM (magnetoresistive random access memory) is a method of storing data bits using magnetic states instead of the electrical charges used by devices such as dynamic random access memory (DRAM).

  • mSATA SSD (mSATA solid-state drive)

    An mSATA SSD is a solid-state drive (SSD) that conforms to the mSATA interface specification developed by the Serial ATA (SATA) International Organization.

  • MTTR (mean time to repair)

    MTTR (mean time to repair) is the average time required to fix a failed component or device and return it to production status.

  • N

    N_Port ID virtualization (NPIV)

    N_Port ID virtualization (NPIV) is a Fibre Channel (FC) standard that makes it possible to create multiple virtual ports on a single physical node port (N_Port), with each virtual port appearing as a unique entity to the FC network.

  • NAND flash memory

    NAND flash memory is a type of non-volatile storage technology that does not require power to retain data.

  • NAND flash wear-out

    NAND flash wear-out is the breakdown of the oxide layer within the floating gate transistors of NAND flash memory.

  • nearline storage

    Nearline storage is the on-site storage of data on removable media.

  • NetApp Data Fabric

    The products and services that compose NetApp’s Data Fabric are designed to provide customers with the agility they need to quickly and efficiently move data to and from the cloud.

  • NetApp SolidFire

    NetApp SolidFire is a business division of NetApp Inc. that specializes in all-flash storage systems.

  • Network Data Management Protocol (NDMP)

    Network Data Management Protocol (NDMP) is an open protocol to control data backup and recovery communications between primary and secondary storage in a heterogeneous network environment.

  • non-volatile memory (NVM)

    Non-volatile memory (NVM) is a type of computer storage medium that retains data even in the absence of a power supply.

  • non-volatile storage (NVS)

    Non-volatile storage (NVS) is a broad collection of technologies and devices that do not require a continuous power supply to retain data or program code persistently on a short- or long-term basis.

  • NOR flash memory

    NOR flash memory is one of two types of non-volatile storage technologies.

  • NVMe (non-volatile memory express)

    NVMe (non-volatile memory express) is a transfer protocol created to accelerate the transfer speed of data in solid-state storage devices.

  • NVMe over Fabrics (NVMe-oF)

    NVMe over Fabrics, also known as NVMe-oF and non-volatile memory express over fabrics, is a protocol specification designed to connect hosts to storage across a network fabric using the NVMe network protocol.

  • NVRAM (non-volatile random access memory)

    NVRAM (non-volatile random access memory) refers to computer memory that can hold data even when power to the memory chips has been turned off.

  • What is an NVDIMM (non-volatile dual in-line memory module)?

    An NVDIMM (non-volatile dual in-line memory module) is hybrid computer memory that retains data during a service outage.

  • What is NetApp?

    NetApp, formerly Network Appliance, Inc., is a multinational corporation in the computer technologies industry specializing in data storage hardware, software and cloud services.

  • What is network-attached storage (NAS)? A complete guide

    Network-attached storage (NAS) is dedicated file storage that enables multiple users and heterogeneous client devices to retrieve data from centralized disk capacity.

  • What is NVMe over Fibre Channel (NVMe over FC)? Definition and Guide

    Non-volatile memory express over Fibre Channel (NVMe over FC) is a technology specification designed to enable NVMe-based message commands to transfer data and status information between a host computer and a target storage subsystem over a Fibre Channel network fabric.

  • O

    object storage

    Object storage, also called object-based storage, is an approach to addressing and manipulating data storage as discrete units, called objects.

  • OpenStack Swift

    OpenStack Swift, also known as OpenStack Object Storage, is an open source object storage system that is licensed under the Apache 2.0 license and runs on standard server hardware.

  • optical disk

    An optical disk is an electronic data storage medium that can be written to and read from using a low-powered laser beam.

  • optical storage

    Optical storage is any storage type in which data is written and read with a laser.

  • orthogonal

    Orthogonal concepts have their roots in advanced mathematics. They are also associated with software development, storage and networking.

  • overprovisioning (SSD overprovisioning)

    Overprovisioning, in a storage context, is the inclusion of extra storage capacity in a solid-state drive.

  • oversubscription

    Oversubscription in a storage area network (SAN) is the practice of committing more network bandwidth to devices connected to that network than what is physically available.

  • P

    parallel file system

    A parallel file system is a software component designed to store data across multiple networked servers.

  • PCIe SSD (Peripheral Component Interconnect Express solid-state drive)

    A PCIe SSD (Peripheral Component Interconnect Express solid-state drive) is a high-speed expansion card that attaches a computer to its peripherals.

  • pebibyte (PiB)

    A pebibyte (PiB) is a unit of measure that describes data capacity.

  • persistent storage

    Persistent storage is any data storage device that retains data after power to that device is shut off.

  • personal cloud storage (PCS)

    Personal cloud storage (PCS) is a local network-attached storage (NAS) device that lets users store data, photos, music, videos and other files and is optimized for media streaming.

  • petabyte

    A petabyte is a measure of memory or data storage capacity that is equal to 2 to the 50th power of bytes.

  • primary storage (main storage)

    Primary storage is the collective methods and technologies that capture and retain digital information in active use and critical for an organization's operations.

  • private cloud storage (internal cloud storage)

    Private cloud storage, also called internal cloud storage, is a service delivery model for storage within a large enterprise.

  • program/erase cycle (P/E cycle)

    A solid-state storage program/erase cycle (P/E cycle) is a sequence of events in which data is written to a solid-state NAND flash memory cell, such as the type found in a flash or thumb drive, and is subsequently erased and rewritten.

  • protected mode

    Protected mode, also called protected virtual address mode, is the primary mode of operation for an Intel-based x86 microprocessor.

  • public cloud storage

    Public cloud storage, also called online storage, is a service model that provides data storage on a pay-per-use basis.

  • Pure Storage

    Pure Storage is a provider of enterprise data flash storage products designed to substitute for electromechanical disk arrays.

  • software portability

    Software portability is a characteristic attributed to a computer program if it can run with minimal rework on operating systems (OSes) other than the one for which it was created.

  • What is a partition in computers?

    A partition is a logical division of a hard disk drive (HDD) that's treated as a separate unit by operating systems (OSes) and file systems.

  • What is parity in computing?

    In computers, parity (from the Latin paritas, meaning "equal or equivalent") is a technique that checks whether data has been lost or written over when it is moved from one place in storage to another or when it is transmitted between computers.

  • What is pay-as-you-go cloud computing (PAYG cloud computing)?

    Pay-as-you-go cloud computing, or PAYG cloud computing, is a payment method for cloud computing that charges based on usage. The practice is similar to that of utility bills, using only resources that are needed.

  • Q

    quad-level cell NAND (QLC NAND)

    Quad-level cell NAND (QLC NAND) is a form of NAND flash memory that can store up to 4 bits of data per memory cell.

  • queue depth

    Queue depth, in storage, is the number of pending input/output (I/O) requests that a storage resource can handle at any one time.

  • R

    race condition

    A race condition is an undesirable situation that occurs when a device or system attempts to perform two or more operations at the same time, but because of the nature of the device or system, the operations must be done in the proper sequence to be done correctly.

  • RAID (redundant array of independent disks)

    RAID (redundant array of independent disks) is a way of storing the same data in different places on multiple hard disks or solid-state drives (SSDs) to protect data in the case of a drive failure.

  • RAID 0 (disk striping)

    RAID 0 (disk striping) is the process of dividing a body of data into blocks and spreading the data blocks across multiple storage devices, such as hard disks or solid-state drives (SSDs), in a redundant array of independent disks group.

  • RAID 10 (RAID 1+0)

    RAID 10, also known as RAID 1+0, is a RAID configuration that combines disk mirroring and disk striping to protect data.

  • RAID 3 (redundant array of independent disks 3)

    RAID 3 (redundant array of independent disks 3) is a RAID configuration that uses a parity disk to store the information generated by a RAID controller and uses striping to store the data.

  • RAID 4 (redundant array of independent disks)

    RAID 4 (redundant array of independent disks) is a RAID configuration that uses a dedicated parity disk and block-level striping across multiple disks.

  • RAID 5

    RAID 5 is a redundant array of independent disks configuration that uses disk striping with parity.

  • RAID 50 (RAID 5+0)

    RAID 50, also known as RAID 5+0, combines distributed parity (RAID 5) with striping (RAID 0). It requires a minimum of six drives.

  • RAID 6

    RAID 6, also known as double-parity RAID, is one of several RAID schemes that work by placing data on multiple disks and enabling I/O operations to overlap in a balanced way, improving performance.

  • RAID controller

    A RAID controller is a hardware device or software program used to manage hard disk drives or solid-state drives in a computer or storage array so they work as a logical unit.

  • RAM (random access memory)

    Random access memory (RAM) is the hardware in a computing device that provides temporary storage for the operating system (OS), software programs and any other data in current use so they're quickly available to the device's processor.

  • RAM-based solid-state drive (SSD)

    A RAM-based solid-state drive (SSD) is a storage device made from silicon microchips that has no moving parts and stores data electronically instead of magnetically.

  • redundant

    Data redundancy refers to the practice of keeping data in two or more places within a database or data storage system.

  • Remote Direct Memory Access (RDMA)

    Remote Direct Memory Access (RDMA) is a technology that enables two networked computers to exchange data in main memory without relying on the processor, cache or operating system of either computer.

  • RRAM or ReRAM (resistive random access memory)

    RRAM, also known as resistive random access memory or ReRAM, is a form of non-volatile storage that operates by changing the resistance of a specially formulated solid dielectric material.

  • S

    SAN switch (storage area network switch)

    A SAN switch (storage area network switch) is a device that connects servers and shared pools of storage devices and is dedicated to moving storage traffic.

  • SAS SSD (Serial-Attached SCSI solid-state drive)

    A SAS SSD (Serial-Attached SCSI solid-state drive) is a NAND flash memory-based storage or caching device designed to fit in the same slot as a hard disk drive (HDD) and use the SAS interface to connect to the host computer.

  • SATA Express (SATAe)

    SATA Express (SATAe or Serial ATA Express) is a bus interface to connect storage devices to a computer motherboard, supporting SATA and PCI Express protocols simultaneously.

  • SCSI (Small Computer System Interface)

    SCSI (Small Computer System Interface) is an electronic interface that enables PCs and servers to communicate with peripheral hardware, such as storage devices, printers and scanners, faster and more flexibly than previous parallel data transfer interfaces.

  • secondary storage

    Secondary storage is persistent storage for noncritical data that doesn't need to be accessed as frequently as data in primary storage or that doesn't have the same performance or availability requirements.

  • semiconductor fab

    A semiconductor fab -- short for fabrication -- is a manufacturing plant in which raw silicon wafers are turned into integrated circuits (ICs).

  • SerDes (serializer/deserializer)

    A SerDes or serializer/deserializer is an integrated circuit (IC or chip) transceiver that converts parallel data to serial data and vice-versa.

  • Serial ATA (Serial Advanced Technology Attachment or SATA)

    Serial ATA (Serial Advanced Technology Attachment or SATA) is a command and transport protocol that defines how data is transferred between a computer's motherboard and mass storage devices, such as hard disk drives (HDDs), optical drives and solid-state drives (SSDs).

  • Serial-Attached SCSI (SAS)

    Serial-Attached SCSI (SAS) is a method used to access computer peripheral devices that employs a serial -- one bit at a time -- means of digital data transfer over thin cables.

  • server-based storage

    Server-based storage is a re-emerging class of data storage that removes cost and complexity by housing storage media inside servers rather than in dedicated and custom-engineered storage arrays.

  • shingled magnetic recording (SMR)

    Shingled magnetic recording (SMR) is a technique for writing data to a hard disk drive (HDD) whereby the data tracks partially overlap to increase the areal density and overall storage capacity per disk.

  • software redundant array of independent disk (software RAID)

    Software RAID, also known as virtual RAID, is a form of RAID (software redundant array of independent disk) performed on an internal server.

  • software-defined storage (SDS)

    Software-defined storage (SDS) is a software program that manages data storage resources and functionality and has no dependencies on the underlying physical storage hardware.

  • solid-state drive (SSD) capacity

    Solid-state drive (SSD) capacity is the maximum amount of data that can be stored on a solid-state drive.

  • solid-state storage

    Solid-state storage is a type of computer storage media that stores data electronically and has no moving parts.

  • solid-state storage garbage collection

    Solid-state storage garbage collection, or SSD garbage collection, is an automated process by which a solid-state drive (SSD) improves write performance.

  • SSD (solid-state drive)

    An SSD, or solid-state drive, is a type of storage device used in computers.

  • SSD caching

    SSD caching, also known as 'flash caching' or 'flash memory caching,' is the temporary storage of frequently-accessed data on NAND flash memory chips in a solid-state drive (SSD) to improve the drive's input/output (I/O) performance and allow data requests to be met with improved speed.