Семейство мэйнфреймов IBM Z: История, архитектура и виртуализация.

Family of mainframe computers

IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest model, the IBM z16, as well as the z15, the z14, and the z13 (released under the IBM z Systems/IBM System z names), the IBM zEnterprise models (in common use the zEC12 and z196), the IBM System z10 models (in common use the z10 EC), the IBM System z9 models (in common use the z9EC) and IBM eServer zSeries models (in common use refers only to the z900 and z990 generations of mainframe).

The zSeries, zEnterprise, System z and IBM Z families were named for their availability – z stands for zero downtime. The systems are built with spare components capable of hot failovers to ensure continuous operations. The IBM Z family maintains full backward compatibility. In effect, current systems are the direct, lineal descendants of the System/360, announced in 1964, and the System/370 from the 1970s. Many applications written for these systems can still run unmodified on the newest IBM Z system over five decades later.

Virtualization is required by default on IBM Z systems. First layer virtualization is provided by the Processor Resource and System Manager (PR/SM) to deploy one or more Logical Partitions (LPARs). Each LPAR supports a variety of operating systems. A hypervisor called z/VM can also be run as the second layer virtualization in LPARs to create as many virtual machines (VMs) as there are resources assigned to the LPARs to support them. The first layer of IBM Z virtualization (PR/SM) allows a z machine to run a limited number of LPARs (up to 80 on the IBM z13). These can be considered virtual "bare metal" servers because PR/SM allows CPUs to be dedicated to individual LPARs. z/VM LPARs allocated within PR/SM LPARs can run a very large number of virtual machines as long as there are adequate CPU, memory, and I/O resources configured with the system for the desired performance, capacity, and throughput. IBM Z's PR/SM and hardware attributes allow compute resources to be dynamically changed to meet workload demands. CPU and memory resources can be non disruptively added to the system and dynamically assigned, recognized, and used by LPARs. I/O resources such as IP and SAN ports can also be added dynamically. They are virtualized and shared across all LPARs. The hardware component that provides this capability is called the Channel Subsystem. Each LPAR can be configured to either "see" or "not see" the virtualized I/O ports to establish desired "shareness" or isolation. This virtualization capability allows significant reduction in I/O resources because of its ability to share them and drive up utilization. PR/SM on IBM Z has earned Common Criteria Evaluation Assurance Level (EAL) 5+ security certification, and z/VM has earned Common Criteria EAL4+ certification. The KVM hypervisor from Linux has also been ported.

Since the move away from the System/390 name, a number of IBM Z models have been released. These can be grouped into families with similar architectural characteristics.

The IBM z16 mainframe, based on the Telum processor, was introduced on April 5, 2022. The instructions for AI and neural nets are described in a new edition of the z/Architecture Principles of Operation.

This line has two generations: first generation, released in 2010/2011 with 114 single rack ("business class") and 196 ("Enterprise class") models; and released in 2012/2013 second generation, branded as generation 12 of main line, and released with two model lines: single rack zBC12 and dual rack zEC12.

Announced on October 3, 2000, and available on December 18, the eServer zSeries 900 (z900 for short) was the first to feature the 64 bit z/Architecture extension of the S/360 architecture, still retaining the support for the 31 bit and 24 bit addressing programs back to 1964. The system's 12 or 20 Blue Flame processors, of which up to 16 could be used as Central Processors, are contained in a multi chip module with 101 glass ceramic layers and 4226 I/O pins. Each processor has 47 million transistors across 177 mm2. Compared to the preceding S/390 G6, the Blue Flame's L1 cache is doubled by splitting it 256+256 KB I+D and the L2 cache is doubled to 32 MB. The peripheral I/O bandwidth has been tripled to 24 GB/s, while the main memory has the bandwidth of 70 GB/s, a 150 ns latency and up to 64 GB capacity. Featuring a 7 stage pipeline, the Blue Flame initially attained 769 MHz with a bulk 180 nm process, and upon the change to silicon on insulator in May 2002 reached 917 MHz, at which it consumes 38 Watts. In 2002, IBM launched the z800, a lower end mainframe featuring five Blue Flames clocked at 625 MHz, of which up to four can be Central Processors, all sharing an 8 MB L2 cache. The I/O bandwidth is 6 GB/s and the memory capacity is up to 32 GB. The fully redesigned z990 mainframes for the mid range and high end became available in June and October 2003, respectively. Featuring IBM's first superscalar CMOS mainframe processors, a dual core chip contained 121 million transistors across 266 mm2, and was manufactured in a 130 nm process, drawing 55 Watts at 1.2 GHz in the z990. Each core contained a cryptographic coprocessor supporting the Data Encryption Standard and SHA 1. It was also the first to be capable of speculative memory disambiguation. The number of logical partitions was doubled to 30, and the maximum distance of Parallel Sysplex rose to 100 km. It took some time for a single OS to fully utilize the z990, as the z/OS and z/VM only gained support for 24 processors in September 2004, and for 32 processors in June 2005 for the z/OS and June 2007 for the z/VM. In May 2004, the z800 was succeeded by the z890. The memory capacity and the core count were left unchanged from the z800, but the processors were the same as in the z990 except clocked at 1.0 GHz. The L2 cache's size was 32 MB, and the I/O subsystem supported two LCSSs and 16 GB/s of bandwidth. A multi chip module is welded onto each processor book for the z196 model.

The typical ordering process of modern IBM Z mainframe looks like a buying of service or looks like a leasing; the mainframe is a program/hardware complex with rent for a system workload, and (in the most cases) additional system capabilities can be unlocked after additional payment.

The z15, z14, z13, zEC12, zBC12, z114 and z196 support the IBM operating systems: z/OS, z/VM, z/VSE, and z/TPF. Other operating systems available include Linux on IBM Z, such as Red Hat Enterprise Linux 6 and SUSE Linux Enterprise Server 11. In November, 2011, IBM introduced Microsoft Windows Server 2008 support via x86 processor based blades that plug into IBM's zEnterprise BladeCenter Extension (zBX). The zBX also supports the IBM WebSphere DataPower Integrated Appliance XI50 for zEnterprise (DataPower XI50z).

The zEnterprise System supports an optional zEnterprise BladeCenter Extension (zBX). This add on infrastructure supports redundant top of Rack switches, redundant power supplies, extra blowers, and IBM BladeCenter chassis. This add on chassis allows POWER7 and x86 blade servers to be integrated with and managed from the mainframe. A gameframe installation at Hoplon Infotainment is an example of a hybrid mainframe. The zBX supports up to 112 blade modules. The zBX and the System Z server are connected by a redundant, secure 10 Gigabit Ethernet connection, providing a private data network. There is also a 1 Gigabit Ethernet connection for management.

The zEnterprise Unified Resource Manager (zManager) allows the supported zBX platforms to be virtualized into a single system for management. It also allows for the prioritization of certain workloads in the system. The Resource Manager can monitor the various platforms for signs of bottlenecks or faults and modify the overall system to recover, maintaining a specified quality of service level.

The zEC12 and z196 support external liquid cooling. Customers have the option of purchasing their mainframe with a water cooled heat exchanger.