Robert J. Dugan

Sharing FCP adapters through virtualization

The IBM System z9TM and its predecessors pioneered server virtualization, including the sharing of data storage subsystems among the virtual servers of a host computer using the channel-sharing capabilities of FICON® channels in Fibre Channel (FC) fabrics. Now industry-standard Small Computer System Interface (SCSI) devices in storage area networks must be shared among host computers using the Fibre Channel Protocol (FCP), and this has been problematic with virtual servers in a host computer. To apply the power of server virtualization to this environment, the IBM System z9 implements a new FC standard called N_Port Identifier Virtualization (NPIV). IBM invented NPIV and offered it as a standard to enable the sharing of host adapters in IBM servers and FC fabrics. With NPIV, a host FC adapter is shared in such a way that each virtual adapter is assigned to a virtual server and is separately identifiable within the fabric. Connectivity and access privileges within the fabric are controlled by identification of each virtual adapter and, hence, the virtual server using each virtual adapter. This paper describes the problem prior to the development of NPIV, the concept of NPIV, and the first implementation of this technique in the FCP channel of the IBM System z9.

System/370 extended architecture: the channel subsystem

The 370-XA channel subsystem architecture represents a significant extension of the corresponding System/370 architecture. This paper examines the need for these extensions, discusses the important features and facilities of the new architecture, and provides comparisons with its predecessor, the System/370 channel architecture. It also describes, from an operational viewpoint, how these new concepts affect I/O processing and how they relate to the current trend toward using multiple CPUs, increasing CPU execution speed, and increasing the number of I/O attachments.