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 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 ...

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 c ...

and

SATA SATA (Serial AT Attachment) is a computer bus interface that connects host adapter, 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) ...

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 ...

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 a ...

, USB and other systems may also be called host adapters. Host adapters can be integrated in the motherboard or be on a separate expansion card. 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. E ...

(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 wor ...

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/I ...

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 Channe ...

allow storage and network functionality over the same physical connection.

SCSI

A SCSI host adapter connects a host system and a peripheral

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 o ...

, linked to the

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

, controls the host adapter itself. In a typical parallel SCSI 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 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, Promise Technology, Adaptec, and

LSI Corporation LSI Logic Corporation, an American company founded in Milpitas, California, was a pioneer in the Application-specific integrated circuit, ASIC and Electronic design automation, EDA industries. It evolved over time to design and sell semiconduct ...

. 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

The term ''host bus adapter'' (HBA) may be used to refer to a

interface card. In this case, it allows devices in a Fibre Channel storage area network 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 and SBus (obsolete today). Each Fibre Channel HBA has a unique World Wide Name (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 tec ...

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 operati ...

. 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 "em ...

. 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 us ...

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 only allows a ''disk'' to talk to the same bus.

SAS and SATA

SAS SAS or Sas may refer to: Arts, entertainment, and media * ''SAS'' (novel series), a French book series by Gérard de Villiers * ''Shimmer and Shine'', an American animated children's television series * Southern All Stars, a Japanese rock ba ...

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.

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, HP, QLogic, Areca,

LSI LSI may refer to: Science and technology * Large-scale integration, integrated circuits with tens of thousands of transistors * Latent semantic indexing, a technique in natural language processing * LSI-11, an early large-scale integration com ...

and ATTO Technology.

eSATA

External Serial ATA (eSATA) disk enclosures and drives are available in the consumer computing market, but not all SATA-compatible motherboards and disk controllers 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 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 ...

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 comput ...

independently, in parallel with CPU (like later

DMA DMA may refer to: Arts * ''DMA'' (magazine), a defunct dance music magazine * Dallas Museum of Art, an art museum in Texas, US * Danish Music Awards, an award show held in Denmark * BT Digital Music Awards, an annual event in the UK * Doctor of M ...

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 tech ...

field), and that executes its own I/O-dedicated programs when pointed to such by the controlling CPU. Protocols used by channel I/O to communicate with peripheral devices include ESCON and newer FICON.

References

{{Reflist

External links

Fibre Channel Host Bus Adapter API
Computer buses SCSI