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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  • G

    GlusterFS (Gluster File System)

    GlusterFS (Gluster File System) is an open source distributed file system that can scale out in building-block fashion to store multiple petabytes of data.

  • green cloud

    Green cloud refers to the potential environmental benefits that green IT services delivered over the internet can offer to individual companies and society as a whole.

  • H

    Hadoop as a service (HaaS)

    Hadoop as a service (HaaS), also known as Hadoop in the cloud, is a big data analytics framework that stores and analyzes data in the cloud using Hadoop.

  • hard disk drive (HDD)

    A computer hard disk drive (HDD) is a non-volatile data storage device.

  • hard drive shredder

    A hard drive shredder is a mechanical device that physically destroys old hard drives in such a way that the data they contain cannot be recovered.

  • hardware RAID (hardware redundant array of independent disk)

    Hardware RAID is a form of RAID where processing is done externally.

  • HD-DVD (high-definition DVD)

    HD-DVD (high-definition DVD) is a defunct high-capacity optical storage medium that was once seen as the successor to the DVD.

  • HDD form factor (hard disk drive form factor)

    HDD form factor is the size or geometry of a hard disk drive, determining the device’s compatibility with the drive bays in a storage array or enclosure, server, portable computer or other computing device.

  • hierarchical storage management (HSM)

    Hierarchical storage management (HSM) is policy-based management of data files that uses storage media economically and without the user being aware of when files are retrieved from storage.

  • holographic storage (holostorage)

    Holographic storage is computer storage that uses laser beams to store computer-generated data in three dimensions.

  • host bus adapter (HBA)

    A host bus adapter (HBA) is a circuit board or integrated circuit adapter that connects a host system, such as a server, to a storage or network device.

  • hot plugging

    Hot plugging is the addition of a component to a running computer system without significant interruption to the operation of the system.

  • How many bytes for...

    Data is often expressed in bytes, which are composed of eight binary digits.

  • 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 and a NAND flash module.

  • I

    I/O virtualization (IOV)

    I/O virtualization (IOV), or input/output virtualization, is technology that uses software to abstract upper-layer protocols from physical connections or physical transports.

  • IBM General Parallel File System (IBM GPFS)

    The IBM General Parallel File System is one of the top file systems used in high-performance computing and the basis for many storage products used in supercomputing.

  • IBM Spectrum

    IBM ships six storage and management software products that fall under the IBM Spectrum umbrella. They provide services such as capacity, data movement and backup.

  • 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 measures the maximum number of reads and writes to non-contiguous storage. It is not an actual benchmark since vendor numbers can vary from real-world performance.

  • IP SAN (Internet Protocol storage area network)

    An IP SAN is a dedicated storage area network (SAN) that allows multiple servers to access pools of shared block storage devices using storage protocols that depend on the Internet Engineering Taskforce standard Internet Protocol suite.

  • 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 iSCSI initiator is software or hardware that enables a host computer to transmit data to an iSCSI-based storage array through a network adapter over a TCP-based IP network.

  • iSCSI switch (Internet Small Computer System Interface switch)

    An iSCSI switch is an appliance that processes and channels data between an iSCSI initiator and target on a storage device.

  • 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.

  • Kryder's Law

    Kryder's Law describes the rate at which former Seagate CTO Mark Kryder predicted disk drive density would grow.

  • 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 System Computer 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)

    As a measure of computer processor storage and real and virtual memory, a megabyte (abbreviated MB) is 2 to the 20th power bytes, or 1,048,576 bytes in decimal notation.

  • megabytes per second (MBps)

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

  • Microsoft Volume Shadow Copy Service (Microsoft VSS)

    Microsoft VSS is a Windows Server feature used for backing up and restoring LUNs and individual files.

  • mirror site

    A mirrored site is a website or set of files on a server that has been copied to another 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.

  • multi-level cell (MLC)

    Multi-level cell flash is a type of NAND flash memory that can store more than 1 bit per cell.

  • 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.

  • NAS enclosure (network-attached storage enclosure)

    NAS enclosures provide shared storage to all users connected to a network, and vary in models appropriate for home offices to enterprises.

  • NAS filer (network-attached storage filer)

    NAS filers add scalable, expandable storage for file-serving purposes in data sharing, cloud applications, Internet and enterprise networks, in both Fibre Channel SANs and Ethernet LANs.

  • nearline storage

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

  • NetApp

    NetApp, formerly Network Appliance Inc., is a company in the computer technologies industry specializing in data storage hardware and associated management software.

  • 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 (NVMe) is a semiconductor technology that does not require a continuous power supply to retain the data or program code stored in a computing device.

  • 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.

  • 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.

  • 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.

  • NVMe over Fibre Channel (NVMe over FC) or FC-NVMe standard

    Nonvolatile memory express over Fibre Channel (NVMe over FC) -- which is implemented through the Fibre Channel-NVMe (FC-NVMe) standard -- 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.

  • 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 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.

  • O

    object storage

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

  • open source storage

    Open source storage is data storage software developed in a public, collaborative manner that permits the free use, distribution and modification of the source code.

  • 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 and to facilitate high-performance access through simultaneous, coordinated input/output operations (IOPS) between clients and storage nodes.

  • parallel I/O

    Parallel I/O is a way of performing multiple input/output operations concurrently, rather than serially.

  • parity

    Parity is a method of detecting errors in data transmissions between computers, while parity bit and parity checking are used in RAID technology to guard against data loss.

  • partition

    Partitioning a hard disk drive is the first step in preparing it for data storage. A disk partition is a carved out logical space used to manage operating systems and files.

  • pay-as-you-go cloud computing (PAYG cloud computing)

    Pay-as-you-go cloud computing (PAYG cloud computing) is a payment method for cloud computing that charges based on usage.

  • 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. It is also sometimes referred to as non-volatile storage.

  • 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.

  • point-in-time snapshot (PIT snapshot)

    Point-in-time snapshots are a method of data protection that allows an administrator to make a full copy of a volume so that a restore can occur based on a specific time.

  • primary storage (main storage)

    Primary storage is the collective methods and technologies used to capture and retain digital information that is 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 solutions 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.

  • Q

    QNAP Systems Inc. (Quality Network Appliance Provider Systems Inc.)

    QNAP Systems Inc. is a Taiwanese-based storage vendor specializing in hardware systems for file sharing, storage management, virtualization and cloud services as well as surveillance applications for home and businesses.

  • 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.

  • Qumulo

    Qumulo is a Seattle-based storage vendor that specializes in selling its data-aware storage software application called the Qumulo Core. This product provides detailed data analytics, and these analytics are meant to help customers better manage their data storage.

  • 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.

  • Rackspace Cloud

    Cloud provider Rackspace offers several different cloud storage services including Cloud Files, Cloud Block Storage and Cloud Backup.

  • 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.

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