To access remote targets, your ESX/ESXi host uses iSCSI initiators. Initiators transport SCSI requests and responses between the ESX/ESXi system and the target storage device on the IP network.

ESX/ESXi supports hardware-based and software-based iSCSI initiators:

Hardware iSCSI Initiator

Uses a specialized iSCSI HBA. The hardware iSCSI initiator is responsible for all iSCSI and network processing and management.

Software iSCSI Initiator

Code built into the VMkernel that allows an ESX/ESXi to connect to the iSCSI storage device through standard network adapters. The software initiator handles iSCSI processing while communicating with the network adapter. With the software initiator, you can use iSCSI technology without purchasing specialized hardware.