A storage area network (SAN) or storage network is a
computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
which provides access to consolidated, block-level data storage. SANs are primarily used to access
data storage
Data storage is the recording (storing) of information (data) in a storage medium. Handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA and DNA are conside ...
devices, such as
disk array
A disk array is a disk storage system which contains multiple disk drives. It is differentiated from a disk enclosure, in that an array has cache memory and advanced functionality, like RAID, deduplication, encryption and virtualization.
Compone ...
s and
tape libraries
In computer storage, a tape library, sometimes called a tape silo, tape robot or tape jukebox, is a storage device that contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges a ...
from
server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients
Role
* Waiting staff, those who work at a restaurant or a bar attending customers and su ...
s so that the devices appear to the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
as
direct-attached storage
Direct-attached storage (DAS) is digital storage directly attached to the computer accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage). DAS consists of one or more storage units such as hard drives ...
. A SAN typically is a dedicated network of storage devices not accessible through the
local area network
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
(LAN).
Although a SAN provides only block-level access,
file systems
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...
built on top of SANs do provide file-level access and are known as
shared-disk file system
A clustered file system is a file system which is shared by being simultaneously mounted on multiple servers. There are several approaches to clustering, most of which do not employ a clustered file system (only direct attached storage for ...
s.
Newer SAN configurations enable hybrid SAN and allow traditional block storage that appears as local storage but also object storage for web services through APIs.
Storage architectures
Storage area networks (SANs) are sometimes referred to as ''network behind the servers'' and historically developed out of a centralized data storage model, but with its own
data network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
. A SAN is, at its simplest, a dedicated network for data storage. In addition to storing data, SANs allow for the automatic
backup
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "back up", w ...
of data, and the monitoring of the storage as well as the backup process. A SAN is a combination of hardware and software. It grew out of data-centric mainframe architectures, where clients in a network can connect to several
server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients
Role
* Waiting staff, those who work at a restaurant or a bar attending customers and su ...
s that store different types of data. To scale storage capacities as the volumes of data grew,
direct-attached storage
Direct-attached storage (DAS) is digital storage directly attached to the computer accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage). DAS consists of one or more storage units such as hard drives ...
(DAS) was developed, where
disk array
A disk array is a disk storage system which contains multiple disk drives. It is differentiated from a disk enclosure, in that an array has cache memory and advanced functionality, like RAID, deduplication, encryption and virtualization.
Compone ...
s or
just a bunch of disks
The most widespread standard for configuring multiple hard disk drives is RAID (Redundant Array of Inexpensive/Independent Disks), which comes in a number of standard configurations and non-standard configurations. Non-RAID drive architectures a ...
(JBODs) were attached to servers. In this architecture, storage devices can be added to increase storage capacity. However, the server through which the storage devices are accessed is a
single point of failure
A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working. SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software appl ...
, and a large part of the LAN network bandwidth is used for accessing, storing and backing up data. To solve the single point of failure issue, a ''direct-attached shared storage'' architecture was implemented, where several servers could access the same storage device.
DAS was the first network storage system and is still widely used where data storage requirements are not very high. Out of it developed the
network-attached storage
Network-attached storage (NAS) is a file-level (as opposed to block-level storage) computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. The term "NAS" can refer to both the tech ...
(NAS) architecture, where one or more dedicated
file server
In computing, a file server (or fileserver) is a computer attached to a network that provides a location for shared disk access, i.e. storage of computer files (such as text, image, sound, video) that can be accessed by the workstations that are ab ...
or storage devices are made available in a LAN. Therefore, the transfer of data, particularly for backup, still takes place over the existing LAN. If more than a terabyte of data was stored at any one time, LAN bandwidth became a bottleneck. Therefore, SANs were developed, where a dedicated storage network was attached to the LAN, and terabytes of data are transferred over a dedicated high speed and bandwidth network. Within the SAN, storage devices are interconnected. Transfer of data between storage devices, such as for backup, happens behind the servers and is meant to be transparent. In a NAS architecture data is transferred using the
TCP
TCP may refer to:
Science and technology
* Transformer coupled plasma
* Tool Center Point, see Robot end effector
Computing
* Transmission Control Protocol, a fundamental Internet standard
* Telephony control protocol, a Bluetooth communication s ...
Ethernet
Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
. Distinct protocols were developed for SANs, such as
Fibre Channel
Fibre Channel (FC) is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data. Fibre Channel is primarily used to connect computer data storage to servers in storage area networks (SAN) in commercial data cen ...
,
iSCSI
Internet Small Computer Systems Interface or iSCSI ( ) is an Internet Protocol-based storage networking standard for linking data storage facilities. iSCSI provides block-level access to storage devices by carrying SCSI commands over a TCP/IP ...
,
Infiniband
InfiniBand (IB) is a computer networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also used ...
. Therefore, SANs often have their own network and storage devices, which have to be bought, installed, and configured. This makes SANs inherently more expensive than NAS architectures.
Components
SANs have their own networking devices, such as SAN switches. To access the SAN, so-called SAN servers are used, which in turn connect to SAN
host adapter
In computer hardware, a host controller, host adapter, or host bus adapter (HBA), connects a computer system bus, which acts as the host system, to other network and storage devices. The terms are primarily used to refer to devices for conne ...
s. Within the SAN, a range of data storage devices may be interconnected, such as SAN-capable disk arrays, JBODS and
tape libraries
In computer storage, a tape library, sometimes called a tape silo, tape robot or tape jukebox, is a storage device that contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges a ...
.
Host layer
Servers that allow access to the SAN and its storage devices are said to form the ''host layer'' of the SAN. Such servers have host adapters, which are cards that attach to slots on the server
motherboard
A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...
(usually PCI slots) and run with a corresponding
firmware
In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...
and
device driver
In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and ot ...
. Through the host adapters the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
of the server can communicate with the storage devices in the SAN.
In Fibre channel deployments, a cable connects to the host adapter through the
gigabit interface converter
A gigabit interface converter (GBIC) is a standard for transceivers, first defined in 1995 and commonly used with Gigabit Ethernet and Fibre Channel for some time. By offering a standard, hot swappable electrical interface, a single gigabit port ...
(GBIC). GBICs are also used on switches and storage devices within the SAN, and they convert digital bits into light impulses that can then be transmitted over the Fibre Channel cables. Conversely, the GBIC converts incoming light impulses back into digital bits. The predecessor of the GBIC was called gigabit link module (GLM).
Fabric layer
The fabric layer consists of SAN networking devices that include SAN switches, routers, protocol bridges, gateway devices, and cables. SAN network devices move data within the SAN, or between an ''initiator'', such as an HBA port of a server, and a ''target'', such as the port of a storage device.
When SANs were first built, hubs were the only devices that were Fibre Channel capable, but Fibre Channel switches were developed and hubs are now rarely found in SANs. Switches have the advantage over hubs that they allow all attached devices to communicate simultaneously, as a switch provides a dedicated link to connect all its ports with one another. When SANs were first built, Fibre Channel had to be implemented over copper cables, these days multimode optical fibre cables are used in SANs.
SANs are usually built with redundancy, so SAN switches are connected with redundant links. SAN switches connect the servers with the storage devices and are typically non-blocking allowing transmission of data across all attached wires at the same time. SAN switches are for redundancy purposes set up in a meshed topology. A single SAN switch can have as few as 8 ports and up to 32 ports with modular extensions. So-called director-class switches can have as many as 128 ports.
In switched SANs, the Fibre Channel switched fabric protocol FC-SW-6 is used under which every device in the SAN has a hardcoded
World Wide Name
A World Wide Name (WWN) or World Wide Identifier (WWID) is a unique identifier used in storage technologies including Fibre Channel, Parallel ATA, Serial ATA, SCSI and Serial Attached SCSI (SAS).
A WWN may be employed in a variety of roles, such ...
(WWN) address in the host bus adapter (HBA). If a device is connected to the SAN its WWN is registered in the SAN switch name server. In place of a WWN, or worldwide port name (WWPN), SAN Fibre Channel storage device vendors may also hardcode a worldwide node name (WWNN). The ports of storage devices often have a WWN starting with 5, while the bus adapters of servers start with 10 or 21.
Storage layer
The serialized Small Computer Systems Interface (SCSI) protocol is often used on top of the Fibre Channel switched fabric protocol in servers and SAN storage devices. The
Internet Small Computer Systems Interface
Internet Small Computer Systems Interface or iSCSI ( ) is an Internet Protocol-based storage networking standard for linking data storage facilities. iSCSI provides block-level storage, block-level access to computer data storage, storage device ...
(iSCSI) over Ethernet and the
Infiniband
InfiniBand (IB) is a computer networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also used ...
protocols may also be found implemented in SANs, but are often bridged into the Fibre Channel SAN. However, Infiniband and iSCSI storage devices, in particular, disk arrays, are available.
The various storage devices in a SAN are said to form the ''storage layer''. It can include a variety of
hard disk
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...
and
magnetic tape
Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magne ...
devices that store data. In SANs, disk arrays are joined through a
RAID
Raid, RAID or Raids may refer to:
Attack
* Raid (military), a sudden attack behind the enemy's lines without the intention of holding ground
* Corporate raid, a type of hostile takeover in business
* Panty raid, a prankish raid by male college ...
which makes a lot of hard disks look and perform like one big storage device. Every storage device, or even partition on that storage device, has a
logical unit number
In computer storage, a logical unit number, or LUN, is a number used to identify a logical unit, which is a device addressed by the SCSI protocol or by Storage Area Network protocols that encapsulate SCSI, such as Fibre Channel or iSCSI.
A LUN m ...
(LUN) assigned to it. This is a unique number within the SAN. Every node in the SAN, be it a server or another storage device, can access the storage by referencing the LUN. The LUNs allow for the storage capacity of a SAN to be segmented and for the implementation of access controls. A particular server, or a group of servers, may, for example, be only given access to a particular part of the SAN storage layer, in the form of LUNs. When a storage device receives a request to read or write data, it will check its access list to establish whether the node, identified by its LUN, is allowed to access the storage area, also identified by a LUN. LUN masking is a technique whereby the host bus adapter and the SAN software of a server restrict the LUNs for which commands are accepted. In doing so LUNs that should never be accessed by the server are masked. Another method to restrict server access to particular SAN storage devices is fabric-based access control, or zoning, which is enforced by the SAN networking devices and servers. Under zoning, server access is restricted to storage devices that are in a particular SAN zone.
Network protocols
A mapping layer to other protocols is used to form a network:
* ATA over Ethernet (AoE), mapping of
AT Attachment
Parallel ATA (PATA), originally , also known as IDE, is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Compaq in 1986 for compatible hard drives and CD or DVD drives. The connection ...
(ATA) over Ethernet
*
Fibre Channel Protocol
Fibre Channel Protocol (FCP) is the SCSI interface protocol utilising an underlying Fibre Channel connection. The Fibre Channel standards define a high-speed data transfer mechanism that can be used to connect workstations, mainframes, supercomput ...
(FCP), a mapping of SCSI over Fibre Channel
*
Fibre Channel over Ethernet
Fibre Channel over Ethernet (FCoE) is a computer network technology that encapsulates Fibre Channel frames over Ethernet networks. This allows Fibre Channel to use 10 Gigabit Ethernet networks (or higher speeds) while preserving the Fibre Channel ...
(FCoE)
*
ESCON
ESCON (Enterprise Systems Connection) is a data connection created by IBM, and is commonly used to connect their mainframe computers to peripheral devices such as disk storage, tape drives and IBM 3270 display controllers. ESCON is an optical ...
over Fibre Channel (
FICON
FICON (Fibre Connection) is the IBM proprietary name for the ANSI ''FC-SB-3 Single-Byte Command Code Sets-3 Mapping Protocol'' for Fibre Channel (FC) protocol. It is a FC layer 4 protocol used to map both IBM's antecedent (either ESCON or para ...
), used by
mainframe computer
A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterpris ...
s
*
HyperSCSI HyperSCSI is an outdated computer network Protocol (computing), protocol for accessing storage by sending and receiving SCSI commands. It was developed by researchers at the Data Storage Institute in Singapore in 2000 to 2003.
HyperSCSI is unlike iS ...
, mapping of SCSI over Ethernet
*
iFCP
Internet Fibre Channel Protocol (iFCP) is a gateway-to-gateway network protocol standard that provides Fibre Channel fabric functionality to Fibre Channel devices over an IP network. It is officially ratified by the Internet Engineering Task Fo ...
iSCSI
Internet Small Computer Systems Interface or iSCSI ( ) is an Internet Protocol-based storage networking standard for linking data storage facilities. iSCSI provides block-level access to storage devices by carrying SCSI commands over a TCP/IP ...
, mapping of SCSI over
TCP/IP
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
*
iSCSI Extensions for RDMA
The iSCSI Extensions for RDMA (iSER) is a computer network protocol that extends the Internet Small Computer System Interface (iSCSI) protocol to use Remote Direct Memory Access ( RDMA). RDMA is provided by either the Transmission Control Protocol ...
(iSER), mapping of iSCSI over
InfiniBand
InfiniBand (IB) is a computer networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also used ...
*
Network block device
On Linux, network block device (NBD) is a network protocol that can be used to forward a block device (typically a hard disk or partition) from one machine to a second machine. As an example, a local machine can access a hard disk drive that is a ...
, mapping
device node
A device is usually a constructed tool. Device may also refer to:
Technology Computing
* Device, a colloquial term encompassing desktops, laptops, tablets, smartphones, etc.
* Device file, an interface of a device driver
* Peripheral, any devic ...
stream socket
A network socket is a software structure within a network node of a computer network that serves as an endpoint for sending and receiving data across the network. The structure and properties of a socket are defined by an application programming ...
s like TCP/IP
*
SCSI RDMA Protocol In computing the SCSI RDMA Protocol (SRP) is a protocol that allows one computer to access SCSI devices attached to another computer via remote direct memory access (RDMA).remote direct memory access (RDMA) transports
Storage networks may also be built using Serial Attached SCSI (SAS) and
Serial ATA
SATA (Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard t ...
(SATA) technologies. SAS evolved from SCSI direct-attached storage. SATA evolved from
Parallel ATA
Parallel ATA (PATA), originally , also known as IDE, is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Compaq in 1986 for compatible hard drives and CD or DVD drives. The connection ...
direct-attached storage. SAS and SATA devices can be networked using SAS Expanders.
Software
The
Storage Networking Industry Association
The Storage Networking Industry Association (SNIA) is a registered 501(c)(6) non-profit trade association incorporated in December 1997. SNIA has more than 185 unique members, 2,000 active contributing members and over 50,000 IT end users and sto ...
(SNIA) defines a SAN as "a network whose primary purpose is the transfer of data between computer systems and storage elements". But a SAN does not just consist of a communication infrastructure, it also has a software ''management layer''. This software organizes the servers, storage devices, and the network so that data can be transferred and stored. Because a SAN does not use
direct attached storage
Direct-attached storage (DAS) is data storage device, digital storage directly attached to the computer accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage). DAS consists of one or more storage unit ...
(DAS), the storage devices in the SAN are not owned and managed by a server. A SAN allows a server to access a large data storage capacity and this storage capacity may also be accessible by other servers. Moreover, SAN software must ensure that data is directly moved between storage devices within the SAN, with minimal server intervention.
SAN management software is installed on one or more servers and management clients on the storage devices. Two approaches have developed in SAN management software: in-band and out-of band management. In-band means that management data between server and storage devices is transmitted on the same network as the storage data. While out-of-band means that management data is transmitted over dedicated links. SAN management software will collect management data from all storage devices in the storage layer. This includes info on read and write failures, storage capacity bottlenecks and failure of storage devices. SAN management software may integrate with the
Simple Network Management Protocol
Simple Network Management Protocol (SNMP) is an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device behaviour. Devices that typically ...
(SNMP).
In 1999 Common Information Model (CIM), an open standard, was introduced for managing storage devices and to provide interoperability, The web-based version of CIM is called Web-Based Enterprise Management (WBEM) and defines SAN storage device objects and process transactions. Use of these protocols involves a CIM object manager (CIMOM), to manage objects and interactions, and allows for the central management of SAN storage devices. Basic device management for SANs can also be achieved through the
Storage Management Interface Specification
Storage may refer to:
Goods Containers
* Dry cask storage, for storing high-level radioactive waste
* Food storage
* Intermodal container, cargo shipping
* Storage tank
Facilities
* Garage (residential), a storage space normally used to store car ...
(SMI-S), were CIM objects and processes are registered in a directory. Software applications and subsystems can then draw on this directory. Management software applications are also available to configure SAN storage devices, allowing, for example, the configuration of zones and LUNs.
Ultimately SAN networking and storage devices are available from many vendors and every SAN vendor has its own management and configuration software. Common management in SANs that include devices from different vendors is only possible if vendors make the
application programming interface
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how t ...
(API) for their devices available to other vendors. In such cases, upper-level SAN management software can manage the SAN devices from other vendors.
Filesystems support
In a SAN, data is transferred, stored and accessed on a block level. As such, a SAN does not provide
data file
A data file is a computer file which stores data to be used by a computer application or system, including input and output data. A data file usually does not contain instructions or code to be executed (that is, a computer program).
Most of the ...
abstraction, only
block-level storage
Block-level storage is a concept in cloud-hosted data persistence where cloud services emulate the behaviour of a traditional block device, such as a physical hard drive.
Storage in such services is organised as blocks. This emulates the type of ...
and operations. Server operating systems maintain their own
file system
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...
s on their own dedicated, non-shared LUNs on the SAN, as though they were local to themselves. If multiple systems were simply to attempt to share a LUN, these would interfere with each other and quickly corrupt the data. Any planned sharing of data on different computers within a LUN requires software.
File systems
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...
have been developed to work with SAN software to provide file-level access. These are known as
shared-disk file system
A clustered file system is a file system which is shared by being simultaneously mounted on multiple servers. There are several approaches to clustering, most of which do not employ a clustered file system (only direct attached storage for ...
.
In media and entertainment
Video editing
Video editing is the manipulation and arrangement of video shots. Video editing is used to structure and present all video information, including films and television shows, video advertisements and video essays. Video editing has been dramaticall ...
systems require very high data transfer rates and very low latency. SANs in media and entertainment are often referred to as serverless due to the nature of the configuration which places the video workflow (ingest, editing, playout) desktop clients directly on the SAN rather than attaching to servers. Control of data flow is managed by a distributed file system. Per-node bandwidth usage control, sometimes referred to as
quality of service
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitat ...
(QoS), is especially important in video editing as it ensures fair and prioritized bandwidth usage across the network.
Quality of service
SAN Storage QoS enables the desired storage performance to be calculated and maintained for network customers accessing the device. Some factors that affect SAN QoS are:
*
Bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
The rate of data throughput available on the system.
* Latency The time delay for a read/write operation to execute.
* Queue depth The number of outstanding operations waiting to execute to the underlying disks (traditional or
solid-state drive
A solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies to store data persistently, typically using flash memory, and functioning as secondary storage in the hierarchy of computer storage. It is ...
s).
Alternatively, over-provisioning can be used to provide additional capacity to compensate for peak network traffic loads. However, where network loads are not predictable, over-provisioning can eventually cause all bandwidth to be fully consumed and latency to increase significantly resulting in SAN performance degradation.
Storage virtualization
Storage virtualization
In computer science, storage virtualization is "the process of presenting a logical view of the physical storage resources to" a host computer system, "treating all storage media (hard disk, optical disk, tape, etc.) in the enterprise as a singl ...
is the process of abstracting logical storage from physical storage. The physical storage resources are aggregated into storage pools, from which the logical storage is created. It presents to the user a logical space for data storage and transparently handles the process of mapping it to the physical location, a concept called
location transparency In computer networks, location transparency is the use of names to identify network resources, rather than their actual location. For example, files are accessed by a unique file name, but the actual data is stored in physical sectors scattered arou ...
. This is implemented in modern disk arrays, often using vendor-proprietary technology. However, the goal of storage virtualization is to group multiple disk arrays from different vendors, scattered over a network, into a single storage device. The single storage device can then be managed uniformly.
Storage hypervisor
Software-defined storage (SDS) is a marketing term for computer data storage software for policy-based provisioning and management of data storage independent of the underlying hardware. Software-defined storage typically includes a form of storag ...
Converged storage
Converged storage is a Computer data storage, storage architecture that combines storage and computing resources into a single entity. This can result in the development of platforms for server centric, storage centric or hybrid workloads where ap ...