DA: Datamover Architecture for the Internet Small Computer System Interface (iSCSI)

The Internet Small Computer System Interface (iSCSI) is a SCSI transport protocol that maps the SCSI family of application protocols onto TCP/IP. Datamover Architecture for iSCSI (DA) defines an abstract model in which the movement of data between iSCSI end nodes is logically separated from the rest of the iSCSI protocol in order to allow iSCSI to adapt to innovations available in new IP transports. While DA defines the architectural functions required of the class of Datamover protocols, it does not define any specific Datamover protocols. Each such Datamover protocol, defined in a separate document, provides a reliable transport for all iSCSI PDUs, but actually moves the data required for certain iSCSI PDUs without involving the remote iSCSI layer itself. This document begins with an introduction of a few new abstractions, defines a layered architecture for iSCSI and Datamover protocols, and then models the interactions within an iSCSI end node between the iSCSI layer and the Datamover layer that happen in order to transparently perform remote data movement within an IP fabric. It is intended that this definition will help map iSCSI to generic Remote Direct Memory Access (RDMA)-capable IP fabrics in the future comprising TCP, the Stream Control Transmission Protocol (SCTP), and possibly other underlying network transport layers, such as InfiniBand. This memo provides information for the Internet community.