So with iSCSI, when we looked at our host architectures we said we had different ways that we could provide iSCSI solutions. We could provide a software iSCSI client or a hardware based solution using an iSCSI HBA.
These 2 solutions are not mutually exclusive. If you’ve got a CPU and you’re not processor bound, you can run it in software (i.e. low cost). If you are processor bound then you would put an iSCSI HBA in. But the only thing it will give you back is CPU cycles.
You can also get native iSCSI targets, (iSCSI storage), for both disk and tape based solutions.
iSCSI was originally developed to allow a host to access storage over IP. If you have already started building Fibre Channel infrastructures we could use an iSCSI Gateway to allow us to consolidate the storage. So an iSCSI Gateway gives an iSCSI Initiator access to the Fibre Channel storage.