ISCSI
In the context of computer storage, Internet SCSI (iSCSI) extends SCSI functionality to operate over TCP/IP. It enables any machine on an IP network (client) to contact any other remote machine (a dedicated host-server) and perform block I/O transfer on it just as it would do on its own local hard disk.The iSCSI protocol uses TCP for its data transfer. Unlike other network storage protocols, such as Fibre Channel-SAN, it requires only the simple and ubiquitous ethernet interface (Gigabit ethernet interface) to operate. This in turn enables centralization of storage without all the usual incompatibility problems associated with various nodes on the network.
Critics of iSCSI expect iSCSI to perform worse than Fibre Channel due to the protocol overhead TCP/IP adds to the communication between client and storage. However new techniques like TCP Offload Engine (TOE) help in reducing this overhead. A Gigabit Ethernet NIC with a TOE offloads the host CPU from the network-related processing and speeds up the data transfer considerably.
The Internet Engineering Task Force ratified iSCSI as an official standard on February 11 2003.
Microsoft announced its support for iSCSI by providing iSCSI inititators in their latest OS and storage server products.