What is iSCSI?
iSCSI stands for internet SCSI, or internet Small Computer Systems Interface.
iSCSI is the transmission of SCSI commands and data over IP networks.
How iSCSI Works
When an application attempts to read from an iSCSI device, the SCSI read command is encapsulated inside an IP packet. The IP packet is then routed just like any other IP packet on the network. When the IP packet reaches its destination, the encapsulation is stripped off and the SCSI read command is interpreted by the iSCSI drive.
SCSI write commands are handled in this same manner.
FCIP (Fibre Channel over IP) is the main competitor to iSCSI.
iSCSI and FCIP represent almost opposite approaches to merging IP and Fibre Channel networks.
FCIP is an implementation of IP on Fibre Channel hardware, whereas iSCSI is an implementation of SCSI on IP hardware.