iSCSI initiator

An Internet Small Computer System Interface (iSCSI) initiator is software or hardware that enables a host computer to send data to an external iSCSI-based storage array through an Ethernet network adapter over a Transmission Control Protocol (TCP)-based Internet Protocol (IP) network. The iSCSI initiator originates the input/output (I/O) command sequence to facilitate data transmission to the storage device, which is also known as an iSCSI target.

 Software-based iSCSI initiators are far more common than hardware-based iSCSI initiators. A software iSCSI initiator is typically part of the server operating system and uses host CPU resources to map the Small Computer System Interface (SCSI) I/O command set to TCP/IP for use by the iSCSI storage system.

 A hardware iSCSI initiator is a dedicated, host-based network interface card (NIC) with built-in resources to handle the iSCSI and TCP/IP processing functions. The need for a NIC-based TCP/IP offload engine (TOE) has declined as servers have gained more powerful processing cores. A hardware iSCSI initiator may still be useful for data protection, when booting a server from a local disk, or for security, if the card has built-in encryption capabilities.

 Special iSCSI name formats to identify initiators and targets include the iSCSI qualified name (IQN), extended unique identifier (EUI), and T11 network address authority (NASA).

This was last updated in December 2015

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