David A. Elko

zSeries features for optimized sockets-based messaging: HiperSockets and OSA-express

In recent years the capacity of mainframe-class servers has grown, and the quantity of data they are required to handle has grown with them. As a result, the existing S/390® I/O architecture required modifications to support an order of magnitude increase in the bandwidth. In addition, new Internet applications increased the demand for improved latency. Adapters were needed to support more users and a larger number of connections to consolidate the external network interfaces. The combination of all of the above requirements presented a unique challenge to server I/O subsystems. With the introduction of the zSeries™ comes an enhanced version of a new I/O architecture for the mainframe called queued direct I/O (QDIO). The architecture was initially exploited for Gigabit and Fast Ethernet adapters. More recently the architecture was exploited by the OSA-Express network adapter for Asynchronous Transfer Mode (ATM) and high-speed Token Ring connections, and it was exploited by HiperSockets for internal LPAR-to-LPAR connections. In each of these features, the TCP/IP stack is changed to tightly integrate the new I/O interface and to offload key TCP/IP functions to hardware facilities. For external communications, the offloaded functions are performed by the OSA-Express hardware microcode; for internal communications, the offloaded functions are performed in the zSeries Licensed Internal Code (LIC). The result is a significant improvement in both latency and bandwidth for sockets-based messaging which is transparent to the exploiting applications.

A locking facility for parallel systems

Clustered and parallel architectures provide the ability to construct systems of high capacity, scalable features, and high availability. In order to provide high throughput in a shared-disk architecture, fundamental advances in multisystem locking technologies are required. This paper describes a locking architecture and operating system support provided for the locking services in a clustered environment. Although initially targeted toward database systems, the functions are general enough for use in many other environments. The paper also describes the products that have deployed this technology.

A Logger system based on web services

The Logger System described in this article is a general purpose set of component interfaces for logging data in a distributed, heterogeneous computing environment. Fundamentally, it serves as an intermediary between log artifact producers and log artifact consumers. It is designed to virtualize existing logging systems including the z/OS® System Logger, Microsoft Windows® event logging, and the UNIX® syslog facility. The Logger System is outlined using the conventions defined in the recently released Web Services Resource Framework (WSRF) and provides an example of how this framework might be used to define a meta-OS (operating system) for grid computing.