A study of iSCSI extensions for RDMA (iSER)

The iSCSI protocol is the IETF standard that maps the SCSI family of application protocols onto TCP/IP enabling convergence of storage traffic on to standard TCP/IP fabrics. The ability to efficiently transfer and place the data on TCP/IP networks is crucial for this convergence of the storage traffic. The iWARP protocol suite provides Remote Direct Memory Access (RDMA) semantics over TCP/IP networks and enables efficient memory-to-memory data transfers over an IP fabric. This paper studies the design process of iSCSI Extensions for RDMA (iSER), a protocol that maps the iSCSI protocol over the iWARP protocol suite. As part of this study, this paper shows how iSER enables efficient data movement for iSCSI using generic RDMA hardware and then presents a discussion of the iWARP architectural features that were conceived during the iSER design. These features potentially enable highly efficient realizations of other I/O protocols as well.