iSCSI

iSCSI is an evolution of the SCSI protocol, which allows SCSI commands to be sent over a network. It allows two hosts to negotiate and then exchange SCSI commands using IP networks. The result is that a remote device with iSCSI capabilities can be seen to be a local disk drive but the commands and data for that device are being sent over the network rather than down a cable in the machine.

There are two parties involved in iSCSI, the iSCSI target and the iSCSI initiator.

An iSCSI target acts as a remote SCSI disk and it can receive SCSI commands and apply them to a local disk, this similar to a 'server'. An iSCSI initiator connects to an iSCSI target and uses the designated disk as a local disk. This is akin to a 'client'.

iSCSI disks behave in exactly the same way as local disks in that you can only have one computer controlling that disk. Therefore, it is important to ensure that only one iSCSI initiator uses any particular iSCSI target. If two (or more) iSCSI initiators use an iSCSI target, there will be data corruption.