iSCSI:- SCSI over the internet.
SCSI (Small computer system interface) – It is the set of standards (protocol) to connecting and transferring data between volumes(machines/peripheral devices ).
The SCSI standards define commands, protocols, electrical and optical interfaces.
SCSI is most commonly used for hard disk drive and tape drives, but it can connect a wide range of other devices, including scanners and CD drives, although not all controllers can handle all devices.
By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances.
iSCSI can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval.
Typically, a computer is an initiator and a data storage device is a target. As in a client-server architecture, an initiator is analogous to the client, and a target is analogous to the server.
In computer data storage, a SCSI initiator is the endpoint that initiates a SCSI session, that is, sends a SCSI command. The initiator usually does not provide any Logical Unit Number (LUNs).
On the other hand, a SCSI target is the endpoint that does not initiate sessions, but instead waits for initiators’ commands and provides required input/output data transfers. The target usually provides to the initiators one or more LUNs because otherwise no read or write command would be possible.