Harry M. Yudenfriend

MVS Dynamic Reconfiguration Management

This paper presents an overview of the Dynamic Reconfiguration Management (DRM) function of MVS/ESA™ and its support of the IBM Enterprise System/9000™ family of machines. Dynamic Reconfiguration Management is the ability to select a new I/O configuration definition without needing to perform a power-on reset (POR) of the hardware or an initial program load (IPL) of the MVS operating system. Dynamic Reconfiguration Management allows the installation to add, delete, or modify definitions for channel paths, control units, and I/O devices, in both the software and hardware I/O configurations.

Multiple-logical-channel subsystems: increasing zSeries I/O scalability and connectivity

With the advent of the z990 multi-book multiprocessor family of server offerings, significant increases in total system capacity and scalability can be realized. Essential to an increased processing capacity is the corresponding need for significant increases in total I/O scalability and connectivity. With the z990, increased I/O capacity is provided by increasing the number of physical I/O channels that can be configured to the system and by restructuring the physical channel subsystem (CSS) into logically distinct channel subsystems. This restructuring is commonly called the multiple-channel subsystem (MCSS) facility. Each logical CSS is then assigned to one or more logical partitions as necessary in order to provide the total I/O connectivity necessary to accommodate the increased processing capacity of the system. An overview of the z990 MCSS architecture is presented with respect to how it is structured, the channel-subsystem constraints that have been removed, and how MCSS functions are provided to the operating systems executing in each of the systems logical partitions (LPARs) in a predominantly transparent manner. Also discussed is the channel-subsystem ardware and firmware (embedded software) design necessary to accommodate the MCSS architecture, as well as overviews of the MCSS I/O configuration process and the z/OS® programming support necessary to accommodate the MCSS facility. Finally, enhancements to the MCSS I/O measurement facility necessary to facilitate autonomic computing are discussed.

Advances in the IBM z13 I/O function and capability

The IBM z13™ introduces a number of significant improvements in the I/O subsystem relative to the IBM zEnterprise™ EC12. This includes advancing the I/O drawer infrastructure to implement generation 3 (Gen 3) of the Peripheral Component Interconnect Express® (PCIe®) links and switches. For the first time on this platform, the PCIe ports are placed directly within the IBM z13 processor itself, reducing latency by avoiding the necessity of using hub chips that have traditionally been implemented for routing and expansion of the PCIe infrastructure. Portions of the processor chip have been reserved to implement the functionality that would previously have resided on these separate hub chips. Traditional I/O features such as Fiber Connection (FICON®), Fibre Channel Protocol (FCP), Open System Adapter (OSA), Crypto Express, and Flash Express are provided with enhanced functionality in the PCIe I/O drawer. The PCIe infrastructure has created the opportunity to integrate additional native PCI adapters. This is further exploited with the use of Single Root I/O virtualization (SR-IOV) capability on a Remote Direct Memory Access over Converged Ethernet (RoCE) Express adapter, which now provides shared exploitation of the facilities within this adapter. An adapter utilizing field programmable gate arrays has been developed to provide compression acceleration in the z13 and forms a foundation for additional varieties of acceleration in the future.

An architecture for storage-hosted application extensions

The very rapid growth of data-intensive computing makes it attractive to perform computations locally, where data is stored. Large storage systems based on standard system technologies with server virtualization capabilities make it feasible to deploy application-specific processing onto the storage system, without jeopardizing the availability of the core storage service or degrading performance. Moreover, price and capacity differences between mainframes and these storage systems make this deployment attractive. We describe the design of a prototype system by which the IBM DS8000™ storage system can host application extensions, called adjuncts, that improve the operation of IBM z/OS® (mainframe) applications. These extensions process large amounts of data in operations such as searching, sorting, and indexing so that the host application need not even access most of the data. The benefits of application extensions result from applying system resources more efficiently. Application processing at the storage system magnifies the total throughput that can be achieved by the host application. Furthermore, by avoiding the transmission of large volumes of data through multiple hardware and software layers, processing often takes a shorter time at a lower cost.

IBM System z I/O discovery and autoconfiguration

IBM zEnterprise®, the latest family of IBM mainframe servers, introduces the System z® input/output (I/O) discovery and autoconfiguration (zDAC) feature. The zDAC feature is the latest step of many I/O-related technologies that simplify the definition and management of I/O configurations for mainframe clients. These I/O technologies provide the autonomic management of I/O requests to meet the workload goals specified by the client policy, dynamically altering the logical I/O configuration to adjust bandwidth capacity required, automatically reacting to hardware and firmware failures to adjust the configuration to maintain optimal availability characteristics, and automatically identifying single points of failure from the host through the I/O fabric to the storage subsystems. This paper describes the zDAC capability and how it complements the autonomic I/O capabilities provided by the IBM z/OS® operating system and IBM mainframes.