Which protocol is used by the iSCSI initiator to communicate with storage targets?

The iSCSI protocol utilizes TCP/IP for communication between the iSCSI initiator and storage targets. This is significant because iSCSI is designed to transport SCSI commands over a TCP/IP network, allowing for the integration of storage area networks (SANs) using standard Ethernet networks. By leveraging TCP/IP, iSCSI can take advantage of existing network infrastructure, reducing costs while providing the necessary reliability and ordering that TCP offers.

Utilizing TCP ensures data packet integrity and reliable delivery, which are crucial for maintaining the performance and reliability of storage communications. This makes it particularly beneficial in virtualized environments where storage access may be a critical factor for performance.

Other protocols like Fibre Channel serve a different purpose and are specific to storage networks, while UDP, though faster, does not provide the same level of reliability that iSCSI requires. NFS (Network File System), on the other hand, is designed primarily for file sharing, not block storage, which distinguishes it from the function that iSCSI serves in storage networking.