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.

  • E

    email archiving

    Email archiving is a systematic approach to saving and protecting the data contained in emails to enable fast retrieval.

  • eMMC (embedded MultiMediaCard)

    An embedded MultiMediaCard (eMMC) is a small storage device made up of NAND flash memory and a simple storage controller.

  • enterprise cloud storage

    Enterprise cloud storage is public cloud storage purchased for a large organization. Enterprise cloud storage can be contrasted with consumer cloud storage, which is often free or purchased at a low price for an individual user's needs.

  • enterprise MLC (eMLC)

    Enterprise MLC (eMLC) is a type of MLC flash that has been enhanced to accommodate more write cycles than consumer-grade MLC flash offers.

  • enterprise SSD (enterprise solid-state drive)

    An enterprise SSD (also known as an enterprise solid-state drive or enterprise solid-state disk) stores data persistently or caches data temporarily in nonvolatile memory and generally provides higher performance and greater endurance than consumer or client SSDs.

  • enterprise storage

    Enterprise storage is a centralized repository for business information that provides common data management, protection and data sharing functions through connections to computer systems.

  • erasure coding

    Erasure coding (EC) is a method of data protection in which data is broken into fragments, expanded and encoded with redundant data pieces and stored across a set of different locations or storage media.

  • exabyte (EB)

    An exabyte (EB) is a large unit of computer data storage, two to the sixtieth power bytes.

  • exbibyte (EiB)

    An exbibyte (EiB) is a unit used to measure data capacity.

  • external storage device

    An external storage device, also referred to as auxiliary storage and secondary storage, is a device that contains all the addressable data storage that is not inside a computer's main storage or memory.

  • F

    FCoE (Fibre Channel over Ethernet)

    FCoE (Fibre Channel over Ethernet) is a storage protocol that enable Fibre Channel (FC) communications to run directly over Ethernet.

  • Fibre Channel

    Fibre Channel is a high-speed networking technology primarily used for transmitting data among data centers, computer servers, switches and storage at data rates of up to 128 Gbps.

  • Fibre Channel adapter

    A Fibre Channel (FC) adapter is a hardware component that provides connectivity from a server to a storage area network (SAN).

  • Fibre Channel Arbitrated Loop (FC-AL)

    A Fibre Channel Arbitrated Loop (FC-AL) is a high-speed Fibre Channel (FC) topology that can connect up to 126 ports on one controller using a one-way loop or hub design.

  • Fibre Channel director (FC director)

    A Fibre Channel (FC) director is a modular, chassis-based, high port-count switch that connects servers, switches and storage in a dedicated FC storage area network (SAN).

  • Fibre Channel port names

    Fibre Channel port names

  • Fibre Channel switch (FC switch)

    A Fibre Channel switch is a networking device that is compatible with the Fibre Channel (FC) protocol and designed for use in a dedicated storage area network (SAN).

  • file storage

    File storage stores data in a hierarchical structure, usually in a NAS system. The system storing data and the client retrieving data see files and folders in the same format.

  • file synchronization (file sync)

    File synchronization, often used as a form of backup, is the process by which files residing in more than one physical location are kept up to date.

  • file system

    In a computer, a file system -- sometimes written filesystem -- is the way in which files are named and where they are placed logically for storage and retrieval.

  • file virtualization

    File virtualization is the creation of an abstraction layer between file servers and the clients that access those file servers... (Continued)

  • file-area network (FAN)

    A file-area network (FAN) is a set of technologies that facilitate file sharing and data management over a network.

  • FLAPE

    FLAPE (flash plus tape) is an approach to tiered storage that allows administrators to archive data as soon as it is written.

  • flash controller (flash memory controller)

    A flash controller is the part of solid-state flash memory that communicates with the host device and manages the flash file system directory.

  • flash file system

    Flash file systems are designed specifically for memory devices. A well-designed flash device and flash file system ensure flash-based capabilities are used efficiently.

  • flash memory

    Flash memory, also known as flash storage, is a type of nonvolatile memory that erases data in units called blocks.

  • flash memory card

    Flash storage memory cards use nonvolatile semiconductor memory to store pictures, audio and video data on portable and remote devices.

  • flash storage

    Flash storage is any type of drive, repository or system that uses flash memory to keep data for an extended period of time.

  • flash-based solid state drive (SSD)

    A flash solid state drive (SSD)  is a non-volatile storage device that stores persistent data in flash memory. 

  • floating gate transistor (FGT)

    A floating gate transistor (FGT) is a complementary metal-oxide semiconductor (CMOS) technology capable of holding an electrical charge in a memory device that is used to store data.

  • FreeNAS Project

    The FreeNAS storage operating system is compatible with most major protocols and storage hardware and provides file sharing in a NAS environment.

  • What is failover?

    Failover is a backup operational mode in which the functions of a system component (such as a processor, server, network, or database, for example) are assumed by secondary system components when the primary component becomes unavailable through either failure or scheduled down time.

  • G

    garbage collection

    Garbage collection is the systematic recovery of pooled computer storage that is being used by a program when that program no longer needs the storage.

  • Ghost

    Ghost is a software product from Symantec that can clone (copy) the entire contents of a hard disk to another computer's hard disk or to storage media.

  • gibibyte (GiB)

    A gibibyte (GiB) is a unit of measure of capacity used in computing.

  • gigabyte (GB)

    A gigabyte (GB) -- pronounced with two hard Gs -- is a unit of data storage capacity that is roughly equivalent to 1 billion bytes.

  • global namespace

    Global namespace is a feature that provides a consolidated view into multiple Network File Systems (NFS), Common Internet File Systems (CIFS), network-attached storage (NAS) systems or file servers that are in different physical locations.

  • 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.

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • green cloud

    Green cloud is a label that describes the potential environmental benefits that information technology services delivered over the Internet can offer society. 

  • green storage

    Green storage is the practice of using a variety of "clean energy" storage methods and products to cut down on a data center's carbon footprint, as well as cost.

  • H

    HA storage (high-availability storage)

    High-availability storage (HA storage) is a storage system that is continuously operational or provides at least 99% uptime.

  • 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.

  • hard zoning

    Hard zoning is used to allocate resources and control access in a storage-area network (SAN).

  • hardware RAID (hardware redundant array of independent disk)

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

  • HD-DVD (high-density DVD)

    HD-DVD (high-density DVD) is an optical digital storage medium with a capacity that far exceeds that of standard DVD media... (Continued)

  • 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.

  • 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.

  • host-based replication

    Host-based replication is the processes of using servers to copy data from one site to another.

  • hot data

    Hot data is a reference to data that is accessed the most by an organization.

  • hot plugging

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

  • hot spare

    A hot spare, also called a hot standby, is a backup component that can be placed into service immediately when a primary component fails. 

  • How many bytes for...

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

  • HSM (Hierarchical Storage Management)

    HSM (Hierarchical Storage Management) is policy-based management of file backup and archiving in a way that uses storage devices economically and without the user needing to be aware of when files are being retrieved from backup storage media.

  • Hybrid Cloud Storage

    Hybrid cloud storage is an approach to managing 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.

  • Hyper-V Virtual Fibre Channel

    Virtual Fibre Channel is a feature in Microsoft Hyper-V 3.0 that lets virtual machines (VMs) connect directly to Fibre Channel (FC)-based storage by using a standard World Wide Name (WWN) associated with a VM.

  • I

    I/O blender effect

    The I/O blender effect is a phenomenon in virtualized environments that degrades storage performance.  The I/O blender effect occurs when multiple virtual machines (VMs) all send their input/output (I/O) streams to a hypervisor for processing.

  • I/O contention (input/output contention)

    I/O contention (input/output contention), occurs when virtual machines compete for I/O resources because there is a limited storage bandwidth.

  • 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 life cycle management (ILM)

    Information life cycle management (ILM) is a comprehensive approach to managing the flow of an information system's data and associated metadata from creation and initial storage to the time when it becomes obsolete and is deleted.

  • Internet Small Computer System Interface (iSCSI) adapter

    An iSCSI adapter is a network interface card that enables the transmission of data between host computers and iSCSI-based storage arrays and typically handles the TCP/IP processing.

  • 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, zetta are among the list of 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 used by mathematics and computer science professionals, along with the general public, when referring to amounts of computer data using the metric system.

  • Kryder's Law

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

  • L

    legacy storage

    Legacy storage is traditional storage hardware that is older and sometimes no longer sold by its vendor.

  • litigation hold (preservation orders or hold orders)

    Litigation hold is a stipulation requiring a company to preserve all data that may relate to a legal action involving the company... (Continued)

  • Load DynamiX

    Load DynamiX is a storage performance testing appliance that can simulate production workloads and virtual desktop infrastructure workloads to determine how a system handles stress before putting that system into production. Appliances support all major storage protocols.

  • 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 management

    LUN management is the process of assigning, provisioning and overseeing logical unit numbers (LUNs) across a storage environment.

  • LUN masking

    LUN masking is a further constraint added to zoning, subdividing access to the port so that only LUNs authorized to access a specific server can access the corresponding port.

  • LUN zoning

    LUN zoning is a method of configuring SAN fabric to match logical unit numbers (LUNs) to the proper servers. As a rule, end devices such as hosts can only see and access storage within their zone. Limiting access in this way improves security and allows bandwidth allocation through assigning particular ports to a zone.

  • M

    M.2 SSD

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

  • managed storage

    Managed storage is the process of offloading an organization’s data storage requirements to an outside managed service provider.

  • 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.

  • multipathing (SAN multipathing)

    Multipathing, also called SAN multipathing or I/O multipathing, is the establishment of multiple physical routes between a server and the storage device that supports it. 

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