Steven G. Glassen

IBM eServer z900 I/O subsystem

The IBM eServer z900 is the first in a generation of future eServers that continues its leadership via a new I/O subsystem with enhancements in capability, performance, configuration management, and qualities of service. Significant features of the I/O subsystem are included to support the 64-bit z/Architecture™ and configuration-management enhancements [e.g., assignable channel path identifiers (CHPIDs) and dynamic channel path management (DCM)]. A 1GB/s self-timed interface (STI), I/O infrastructure, and I/O card cage are described which support the high-bandwidth I/O (e.g., FICON™, Ethernet). These improvements yield enhanced configuration flexibility and connectivity, as well as reliability, availability, and serviceability (RAS), while providing for future bandwidth growth. The various types of I/O ports supported by the IBM eServer z900 platform are also discussed. A common I/O platform is discussed which has been used to provide a uniform, high-bandwidth attachment of industry-standard peripheral computer interface (PCI) cards, while maintaining the leadership functionality and RAS of the eServer zSeries™. A high-density (16-port) ESCON® I/O card has been designed by exploiting IBM advanced CMOS and state-of-the-art fiber optic technologies. Finally, a high-performance, high-density intersystem channel (ISC-3) coupling link I/O card has been developed for the IBM eServer z900 by leveraging advanced technology and packaging techniques.

Redundant I/O interconnect

The outstanding reliability, availability, and serviceability (RAS) characteristics of IBM mainframe computers are among the features that gained the IBM eServerTM family its reputation as a leading platform for business-critical applications. The aim now is to further improve IBM System z9® RAS by introducing redundant I/O interconnect (RII) as a building block of enhanced book availability and recovery scenarios. RH provides a means of maintaining I/O connectivity during planned or unplanned outages in a way that is transparent to the operating system and customer applications. The mechanism that meets this requirement is the provision of an alternate path to the I/O cage, which provides high-bandwidth I/O slots to enable a higher number of I/O ports per card. This paper discusses the I/O subsystem hardware and firmware aspects of RII.