A Host Bus Adapter (HBA) is an interface card linking a host to a Storage Area Network (SAN). More accurately known as a Host I/O Controller, an HBA is an integrated circuit adapter and/or circuit board that provides physical connectivity and input/output (I/O) processing between a storage device and a server.

The HBA enhances server performance by relieving the host microprocessor of retrieval tasks and data storage. An HBA and its related disk subsystems are also known as a disk channel.

The HBA connects a computer’s host system to other network and storage devices. The HBA is also called a host controller or host adapter. The latter terms mainly denote devices that link SCSI, Fibre Channel, and eSATA devices. It is also used to refer to devices connecting to IDE, Ethernet, FireWire, Universal Serial Bus (USB), and other systems.

Recent technological developments such as iSCSI have resulted in Ethernet HBAs. Ethernet HBAs differ from Ethernet NICs because the latter use hardware iSCSI- dedicated TCP Offload Engines.

The Small Computer System Interface (SCSI) is a host adapter connecting a computer to a peripheral device like an SCSI bus. This HBA bridges the gap between the SCI bus and the computer host’s internal bus.

The Fibre Channel (FC) is a technology used for storage networking. The HBA often refers to the FC interface card. Major open systems, buses, and computer architectures use Fibre Channel HBAs.

The External Serial Advanced Technology Attachment (eSATA) is a bus mainly intended for the transmission of information between mass storage devices such as optical drives and hard disk drives in a computer. It is a SATA variant used for external connectivity.

Integrated Drive Electronics (IDE) is a hardware interface used mainly to tape drives, optical disks, and hard disks to a PC. IDE drives are also known as Advanced Technology Attachment (ATA) drives.

Ethernet is a Local Area Network (LAN) computer networking technology.

FireWire is a serial bus interface standard mostly used in PCs. This interface involves real-time data transfer and high-speed communications. FireWire is the Apple brand name for the IEEE 1394 interface.

Universal Serial Bus (USB) is a standard HBA that serves as an interface between devices to a computer host. This was created to connect numerous peripherals through one standard socket. USB enhances the plug-and-play capacity by permitting hot-swapping. This allows devices to be connected and disconnected without deactivating the device or rebooting the PC.