![Controller SCSI](https://upload.wikimedia.org/wikipedia/commons/b/b2/Controller_SCSI.JPG)
In
computer hardware
Computer hardware includes the physical parts of a computer, such as the computer case, case, central processing unit (CPU), Random-access memory, random access memory (RAM), Computer monitor, monitor, Computer mouse, mouse, Computer keyboard, ...
, a host controller, host adapter, or host bus adapter (HBA), connects a
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
system bus
A system bus is a single computer bus that connects the major components of a computer system,
combining the functions of a data bus to carry information, an address bus to determine where it should be sent or read from, and a control bus to dete ...
, which acts as the host system, to other
network
Network, networking and networked may refer to:
Science and technology
* Network theory, the study of graphs as a representation of relations between discrete objects
* Network science, an academic field that studies complex networks
Mathematics
...
and
storage devices. The terms are primarily used to refer to devices for connecting
SCSI
Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interface ...
,
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 ...
and
SATA
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 to ...
devices.
Devices for connecting to
IDE,
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 ...
,
FireWire
IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony an ...
,
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
and other systems may also be called host adapters.
Host adapters can be integrated in the motherboard or be on a separate
expansion card
In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus slo ...
.
The term
network interface controller
A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) is a computer hardware component that connects a computer to a computer network.
Ear ...
(NIC) is more often used for devices connecting to computer networks, while the term
converged network adapter
A converged network adapter (CNA), also called a converged network interface controller (C-NIC), is a computer input/output device that combines the functionality of a host bus adapter (HBA) with a network interface controller (NIC). In other words ...
can be applied when protocols such as
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 ...
or
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 ...
allow storage and network functionality over the same physical connection.
SCSI
A SCSI host adapter connects a host system and a peripheral
SCSI
Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interface ...
device or storage system. These adapters manage service and task communication between the host and target.
Typically a
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 ...
, linked 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 ...
, controls the host adapter itself.
In a typical
parallel SCSI
Parallel SCSI (formally, SCSI Parallel Interface, or SPI) is the earliest of the interface implementations in the SCSI family. SPI is a parallel bus; there is one set of electrical connections stretching from one end of the SCSI bus to the othe ...
subsystem, each device has assigned to it a unique numerical ID. As a rule, the host adapter appears as SCSI ID 7, which gives it the highest priority on the SCSI bus (priority descends as the SCSI ID descends; on a 16-bit or "wide" bus, ID 8 has the lowest priority, a feature that maintains compatibility with the priority scheme of the 8-bit or "narrow" bus).
The host adapter usually assumes the role of
SCSI initiator
In computer data storage, a SCSI initiator is the endpoint that initiates a SCSI session, that is, sends a SCSI command. The initiator usually does not provide any Logical Unit Numbers (LUNs).
On the other hand, a SCSI target is the endpoint that ...
, in that it issues commands to other SCSI devices.
A computer can contain more than one host adapter, which can greatly increase the number of SCSI devices available.
Major SCSI adapter manufacturers are
HP,
ATTO Technology
ATTO Technology, Inc. is a manufacturer of storage connectivity products for data-intensive computing. ATTO manufactures Fibre Channel and SAS/SATA host bus adapters, RAID adapters, Fibre Channel switches, protocol conversion bridges, storage ...
, Promise Technology,
Adaptec
Adaptec was a computer storage company and remains a brand for computer storage products. The company was an independent firm from 1981 to 2010, at which point it was acquired by PMC-Sierra, which itself was later acquired by Microsemi, which itse ...
, and
LSI Corporation
LSI Logic Corporation, an American company founded in Milpitas, California, was a pioneer in the ASIC and EDA industries. It evolved over time to design and sell semiconductors and software that accelerated storage and networking in data cente ...
. LSI, Adaptec, and ATTO offer PCIe SCSI adapters which fit in Apple Mac, on Intel PCs, and low-profile motherboards which lack SCSI support due to the inclusion of SAS and/or SATA connectivity.
Fibre Channel
![Host-Bus-Adapter-(HBA)](https://upload.wikimedia.org/wikipedia/commons/a/a6/Host-Bus-Adapter-%28HBA%29.jpg)
The term ''host bus adapter'' (HBA) may be used to refer to a
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 ...
interface card. In this case, it allows devices in a Fibre Channel
storage area network
A storage area network (SAN) or storage network is a computer network which provides access to consolidated, block-level data storage. SANs are primarily used to access data storage devices, such as disk arrays and tape libraries from serve ...
to communicate data between each otherit may connect a server to a switch or storage device, connect multiple storage systems, or connect multiple servers.
Fibre Channel HBAs are available for
open systems, computer architectures, and buses, including
PCI
PCI may refer to:
Business and economics
* Payment card industry, businesses associated with debit, credit, and other payment cards
** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors
* Pro ...
and
SBus
SBus is a computer bus system that was used in most SPARC-based computers (including all SPARCstations) from Sun Microsystems and others during the 1990s. It was introduced by Sun in 1989 to be a high-speed bus counterpart to their high-speed S ...
(obsolete today).
Each Fibre Channel HBA has a unique
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, s ...
(WWN), which is similar to an Ethernet
MAC address
A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking techno ...
in that it uses an
OUI assigned by the
IEEE
The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...
. However, WWNs are longer (8 bytes). There are two types of WWNs on a HBA; a node WWN (WWNN), which is shared by all ports on a host bus adapter, and a port WWN (WWPN), which is unique to each port. There are HBA models of different speeds: 1Gbit/s, 2Gbit/s, 4Gbit/s, 8Gbit/s, 10Gbit/s, 16Gbit/s, 20Gbit/s and 32Gbit/s.
The major Fibre Channel HBA manufacturers are
QLogic and
Broadcom
Broadcom Inc. is an American designer, developer, manufacturer and global supplier of a wide range of semiconductor and infrastructure software products. Broadcom's product offerings serve the data center, networking, software, broadband, wirel ...
. As of mid-2009, these vendors shared approximately 90% of the market.
[Mellor, Chris]
"HBA market share shenanigans"
''The Register'', 2009-08-14. Also based on Dell'Oro data. Other manufacturers include
Agilent
Agilent Technologies, Inc. is an American life sciences company that provides instruments, software, services, and consumables for the entire laboratory workflow. Its global headquarters is located in Santa Clara, California. Agilent was establi ...
,
ATTO, and
Brocade
Brocade is a class of richly decorative shuttle-woven fabrics, often made in colored silks and sometimes with gold and silver threads. The name, related to the same root as the word "broccoli", comes from Italian ''broccato'' meaning "embos ...
.
HBA is also known to be interpreted as High Bandwidth Adapter in cases of Fibre Channel controllers.
InfiniBand
The term (HCA) is usually used to describe
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 ...
interface cards.
ATA
ATA host adapters are integrated into motherboards of most modern
PCs. They are often improperly called ''disk controllers''. The correct term for the component that allows a computer to talk to a peripheral bus is ''host adapter'' . A proper
disk controller
{{unreferenced, date=May 2010
The disk controller is the controller circuit which enables the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. It also provides an interface between the disk drive and the bus conne ...
only allows a ''disk'' to talk to the same bus.
SAS and SATA
SAS or serial-attached SCSI is the current connectivity to replace the previous generation parallel-attached SCSI (PAS) devices. Ultra320 was the highest level of parallel SCSI available, but SAS has since replaced it as the highest-performing SCSI technology.
SATA
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 to ...
is a similar technology from the aspect of connection options. HBAs can be created using a single connector to connect both SAS and SATA devices.
Major SAS/SATA adapter manufacturers are Promise Technologies,
Adaptec
Adaptec was a computer storage company and remains a brand for computer storage products. The company was an independent firm from 1981 to 2010, at which point it was acquired by PMC-Sierra, which itself was later acquired by Microsemi, which itse ...
,
HP,
QLogic, Areca,
LSI and
ATTO Technology
ATTO Technology, Inc. is a manufacturer of storage connectivity products for data-intensive computing. ATTO manufactures Fibre Channel and SAS/SATA host bus adapters, RAID adapters, Fibre Channel switches, protocol conversion bridges, storage ...
.
eSATA
External Serial ATA (eSATA)
disk enclosure
A disk enclosure is a specialized casing designed to hold and power disk drives while providing a mechanism to allow them to communicate to one or more separate computers.
Drive enclosures provide power to the drives therein and convert the dat ...
s and drives are available in the consumer computing market, but not all SATA-compatible motherboards and
disk controller
{{unreferenced, date=May 2010
The disk controller is the controller circuit which enables the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. It also provides an interface between the disk drive and the bus conne ...
s include eSATA ports. As such, adapters to connect eSATA devices to ports on an internal SATA bus are available.
Mainframe channel I/O
In the
mainframe field, the terms ''host adapter'' or ''host bus adapter'' were traditionally not used.
A similar goal was achieved since the 1960s with channel I/O, a separate processor that can access
main memory
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers.
The central processing unit (CPU) of a computer ...
independently, in parallel with CPU (like later
DMA in
personal computer
A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
field), and that executes its own I/O-dedicated
program
Program, programme, programmer, or programming may refer to:
Business and management
* Program management, the process of managing several related projects
* Time management
* Program, a part of planning
Arts and entertainment Audio
* Progra ...
s when pointed to such by the controlling CPU.
Protocols used by channel I/O to communicate with
peripheral device
A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...
s include
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 ...
and newer
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 ...
.
See also
*
Fibre Channel Host Bus Adapters
*
Host controller interface for USB and FireWire host adapter information
References
{{Reflist
External links
Fibre Channel Host Bus Adapter API
Computer buses
SCSI