Host adapter

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Fibre Channel host bus adapter (a 64-bit PCI-X card) QLA 2200F.jpg
Fibre Channel host bus adapter (a 64-bit PCI-X card)
SCSI host adapter (a 16-bit ISA card) Controller SCSI.JPG
SCSI host adapter (a 16-bit ISA card)

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. [1] The terms are primarily used to refer to devices for connecting SCSI, SAS, NVMe, Fibre Channel and SATA devices. [2] Devices for connecting to FireWire, USB and other devices may also be called host controllers or host adapters.

Contents

Host adapters can be integrated in the motherboard or be on a separate expansion card. [3]

The term network interface controller (NIC) is more often used for devices connecting to computer networks, while the term converged network adapter can be applied when protocols such as iSCSI or Fibre Channel over Ethernet allow storage and network functionality over the same physical connection.

SCSI

A SCSI host adapter connects a host system and a peripheral SCSI device or storage system. These adapters manage service and task communication between the host and target. [2] Typically a device driver, linked to the operating system, 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, 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

Fibre Channel host bus adapter Host-Bus-Adapter-(HBA).jpg
Fibre Channel host bus adapter

The term host bus adapter (HBA) may be used to refer to a Fibre Channel interface card. In this case, it allows devices in a Fibre Channel storage area network to communicate data between each other it may connect a server to a switch or storage device, connect multiple storage systems, or connect multiple servers. [2] 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 in that it uses an OUI assigned by the IEEE. 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: 1 Gbit/s, 2 Gbit/s, 4 Gbit/s, 8 Gbit/s, 10 Gbit/s, 16 Gbit/s, 20 Gbit/s and 32 Gbit/s.

The major Fibre Channel HBA manufacturers are QLogic and Broadcom. As of mid-2009, these vendors shared approximately 90% of the market. [4] [5] Other manufacturers include Agilent, ATTO, and Brocade.

HBA is also known to be interpreted as High Bandwidth Adapter in cases of Fibre Channel controllers.

InfiniBand

The term host channel adapter (HCA) is usually used to describe InfiniBand interface cards. [2]

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[ citation needed ]. A proper disk controller 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 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 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 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 independently, in parallel with CPU (like later DMA in personal computer field), and that executes its own I/O-dedicated programs when pointed to such by the controlling CPU.[ citation needed ]

Protocols used by channel I/O to communicate with peripheral devices include ESCON and newer FICON.

See also

Related Research Articles

<span class="mw-page-title-main">SCSI</span> Set of computer and peripheral connection standards

Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced in the 1980s and has seen widespread use on servers and high-end workstations, with new SCSI standards being published as recently as SAS-4 in 2017.

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 network. iSCSI facilitates data transfers over intranets and to manage storage over long distances. It can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval.

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 centers.

<span class="mw-page-title-main">SATA</span> Computer bus interface for storage devices

SATA 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 become the predominant interface for storage devices.

<span class="mw-page-title-main">Disk controller</span> Controller for disk storage, usually integrated into the drive

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 connecting it to the rest of the system.

A disk array controller is a device that manages the physical disk drives and presents them to the computer as logical units. It almost always implements hardware RAID, thus it is sometimes referred to as RAID controller. It also often provides additional disk cache.

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).

<span class="mw-page-title-main">Serial Attached SCSI</span> Point-to-point serial protocol for enterprise storage

In computing, Serial Attached SCSI (SAS) is a point-to-point serial protocol that moves data to and from computer-storage devices such as hard disk drives and tape drives. SAS replaces the older Parallel SCSI bus technology that first appeared in the mid-1980s. SAS, like its predecessor, uses the standard SCSI command set. SAS offers optional compatibility with Serial ATA (SATA), versions 2 and later. This allows the connection of SATA drives to most SAS backplanes or controllers. The reverse, connecting SAS drives to SATA backplanes, is not possible.

<span class="mw-page-title-main">Adaptec</span> Computer storage company

Adaptec, Inc., 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 itself was later acquired by Microchip Technology.

A SCSI connector is used to connect computer parts that communicate with each other via the SCSI standard. Generally, two connectors, designated male and female, plug together to form a connection which allows two components, such as a computer and a disk drive, to communicate with each other. SCSI connectors can be electrical connectors or optical connectors. There have been a large variety of SCSI connectors in use at one time or another in the computer industry. Twenty-five years of evolution and three major revisions of the standards resulted in requirements for Parallel SCSI connectors that could handle an 8, 16 or 32 bit wide bus running at 5, 10 or 20 megatransfer/s, with conventional or differential signaling. Serial SCSI added another three transport types, each with one or more connector types. Manufacturers have frequently chosen connectors based on factors of size, cost, or convenience at the expense of compatibility.


Serial general purpose input/output (SGPIO) is a four-signal bus used between a host bus adapter (HBA) and a backplane. Of the four signals, three are driven by the HBA and one by the backplane. Typically, the HBA is a storage controller located inside a server, desktop, rack or workstation computer that interfaces with hard disk drives or solid state drives to store and retrieve data. It is considered an extension of the general-purpose input/output (GPIO) concept.

<span class="mw-page-title-main">ATTO Technology</span> Storage connectivity product manufacturer

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 controllers, MacOS iSCSI initiator software and acceleration software with storage interface connectivity to SATA, SAS, Fibre Channel, Thunderbolt devices, Ethernet and NVMe.

<span class="mw-page-title-main">Storage area network</span> Network which provides access to consolidated, block-level data storage

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 servers so that the devices appear to the operating system as direct-attached storage. A SAN typically is a dedicated network of storage devices not accessible through the local area network (LAN).

<span class="mw-page-title-main">Dell M1000e</span> Server computer

The Dell blade server products are built around their M1000e enclosure that can hold their server blades, an embedded EqualLogic iSCSI storage area network and I/O modules including Ethernet, Fibre Channel and InfiniBand switches.

<span class="mw-page-title-main">Converged network adapter</span> Computer input/output device

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, it "converges" access to, respectively, a storage area network and a general-purpose computer network.

ThunderLink is a legacy expansion adapter for the Thunderbolt computer bus interface, which added support for SAS, SATA, fibre optic and Ethernet interfaces.

Hard disk drives are accessed over one of a number of bus types, including parallel ATA, Serial ATA (SATA), SCSI, Serial Attached SCSI (SAS), and Fibre Channel. Bridge circuitry is sometimes used to connect hard disk drives to buses with which they cannot communicate natively, such as IEEE 1394, USB, SCSI, NVMe and Thunderbolt.

<span class="mw-page-title-main">SCST</span>

SCST is a GPL licensed SCSI target software stack. The design goals of this software stack are high performance, high reliability, strict conformance to existing SCSI standards, being easy to extend and easy to use. SCST does not only support multiple SCSI protocols but also supports multiple local storage interfaces and also storage drivers implemented in user-space via the scst_user driver.

<span class="mw-page-title-main">SATA Express</span> Computer device interface

SATA Express is a computer bus interface that supports both Serial ATA (SATA) and PCI Express (PCIe) storage devices, initially standardized in the SATA 3.2 specification. The SATA Express connector used on the host side is backward compatible with the standard SATA data connector, while it also provides two PCI Express lanes as a pure PCI Express connection to the storage device.

Enterprise Storage OS, also known as ESOS, is a Linux distribution that serves as a block-level storage server in a storage area network (SAN). ESOS is composed of open-source software projects that are required for a Linux distribution and several proprietary build and install time options. The SCST project is the core component of ESOS; it provides the back-end storage functionality.

References

  1. "Host Adapter". Technopedia. Retrieved 2 July 2019.
  2. 1 2 3 4 Rouse, Margaret; Sliwa, Carol (April 2015). "host bus adapter (HBA)". SearchStorage. TechTarget. Retrieved 2 July 2019.
  3. "Host adapter". Computer Hope.
  4. Simpson, Dave. "Emulex vs. QLogic: Who's on first?", InfoStor, 2009-08-14. Market share for Q2 2009 according to a proprietary report from Dell'Oro Group.
  5. Mellor, Chris. "HBA market share shenanigans", The Register, 2009-08-14. Also based on Dell'Oro data.