VMWare ISCSI Storage

The iSCSI protocol is a transport for SCSI over TCP/IP. Traditional storage area networks (SANs) leveraged fiber channel protocol (FCP) to connect servers to consolidated storage for block level access. Fiber channel was the protocol of choice mainly for performance. The initial release of fiber channel was 1Gbps vs. Ethernet 100Mbps speeds at the time. Furthermore, FCP was optimized for storage networking—non blocking, no TCP/IP overhead, and optimized for larger block I/O.

iSCSI was available and functional with 100BaseT Ethernet, however iSCSI gained significant momentum as Gigabit Ethernet became the standard in corporate data centers. Customers began to embrace iSCSI as a lower cost alternative to fiber channel. Initially, most approached iSCSI with caution using it for test/dev environments only. Today, iSCSI is utilized in production environments to connect business critical servers to consolidated storage. Similar capabilities used with fiber channel such as path failover, server cluster support, and the ability to aggregate multiple ports together to increase I/O allow high performance, highly available ‘iSANs’ to be built using lower cost Ethernet switches and NICs vs more expensive fiber channel switches and HBAs.