An Internet Small Computer System Interface (iSCSI) adapter is a network interface card (NIC) that enables the transmission of data between a host computer and an iSCSI-based storage array over Ethernet and TCP/IP network infrastructures.
The iSCSI adapter, also known as an iSCSI host bus adaptor (HBA) or iSCSI NIC, facilitates the mapping of Small Computer System Interface (SCSI) commands to TCP/IP to allow the input/output (I/O) of data with iSCSI-based storage systems. The iSCSI adapter typically includes a network interface controller, a TCP/IP offload engine (TOE), and a SCSI adapter. The adapter hardware handles the iSCSI and TCP/IP processing functions to conserve the host's CPU processing power for server applications and to increase iSCSI storage area network (SAN) performance.
A hardware-based iSCSI adapter generally can provide higher levels of performance than a software iSCSI initiator, but the need for iSCSI initiator hardware has declined with the emergence of servers equipped with more powerful processing cores.