In computer hardware, a host controller, host adapter, or host bus adapter (HBA) connects a host system (the computer) to other network and storage devices.
A host bus adapter (HBA) is a circuit board and/or integrated circuit adapter that provides input/output (I/O) processing and physical connectivity between a server and a storage device. Because the HBA relieves the host microprocessor of both data storage and retrieval tasks, it can improve the server’s performance time. An HBA and its associated disk subsystems are sometimes referred to as a disk channel.
Single HBA Cards have two ports
Each 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: 1Gbit/s, 2Gbit/s, 4Gbit/s, 8Gbit/s, 16Gbit/s, 10Gbit/s and 20Gbit/s.