IBM Z

IBM Z
Company type	Product line
Industry	Computer hardware
Predecessor	IBM z Systems
Founded	July 2017; 9 years ago
Products	IBM z17, IBM z16, IBM z15, IBM z14, IBM z13, IBM zEnterprise (zEC12, z196), System z10 (z10 EC), System z9 (z9EC), eServer zSeries (z900, z990)
Owner	IBM

IBM Z represents IBM's line of z/Architecture mainframe computers. Since July 2017, the designation shifted from IBM z Systems to IBM Z, which includes models like the IBM z17, z16, z15, z14, and z13 (formerly part of IBM z Systems/IBM System z), along with earlier generations such as IBM zEnterprise (zEC12, z196), System z10 (z10 EC), System z9 (z9EC), and eServer zSeries (z900, z990).

Architecture

The product lines zSeries, zEnterprise, System z, and IBM Z highlight exceptional reliability—where z signifies zero downtime. These platforms incorporate redundant components and hot failover mechanisms designed to guarantee uninterrupted availability.

IBM Z ensures complete backward compatibility with all preceding systems dating back to the System/360 introduced in 1964 and the System/370 from the 1970s, allowing numerous legacy applications to operate unchanged on modern hardware.

Virtualization

Virtualization is a core feature of IBM Z machines. The main virtualization layer, Processor Resource and System Manager (PR/SM), facilitates the creation of multiple Logical Partitions (LPARs), each capable of running distinct operating systems. Within these LPARs, a secondary hypervisor called z/VM can host many virtual machines, limited only by the resources allocated.

Models such as the IBM z13 support up to 80 LPARs via PR/SM, with CPUs assigned at the LPAR level to deliver performance comparable to direct hardware access. CPU, memory, and I/O resources may be dynamically adjusted or reassigned without causing interruptions. The Channel Subsystem virtualizes I/O channels across LPARs, enabling flexible resource sharing or isolation according to configuration needs, thereby improving efficiency and minimizing hardware requirements.

Security certifications include Common Criteria EAL5+ for PR/SM and EAL4+ for z/VM. Furthermore, the Linux-based Kernel-based Virtual Machine (KVM) hypervisor has been adapted for IBM Z platforms, broadening virtualization capabilities.

List of models (reverse chronological order)

Following the discontinuation of the System/390 brand, IBM has released multiple IBM Z models categorized by architecture families.

IBM z17

Unveiled at Hot Chips 2024, the IBM z17 mainframe features the Telum II processor with a 43 billion-transistor die that integrates an on-chip DPU and supports OpenCAPI. This model offers incremental advancements over the previous generation's Telum processor found in the z16.

IBM z16

Released on April 5, 2022, the IBM z16 mainframe incorporates the Telum processor and introduces real-time AI capabilities for large-scale transaction processing. It is also recognized as the industry's first quantum-safe platform. AI and neural network instruction details are documented in the fourteenth edition of the z/Architecture Principles of Operation.

IBM z15

The IBM z15 (8561) mainframe debuted on September 12, 2019, powered by the z15 chip.
Extensive technical documentation such as the IBM z15 Technical Introduction and IBM z15 Technical Guide provide in-depth coverage of its design and features.

IBM z14

Launched initially as a dual-frame system in July 2017 and subsequently as a single-frame model in April 2018, the IBM z14 utilizes the z14 chip, a 5.2 GHz processor with 10 cores. A single system can support up to 240 Processing Unit (PU) cores, with 170 configurable for customer workloads, alongside up to 32 TB of usable redundant array of independent memory (RAIM), part of which can be assigned as Virtual Flash Memory (VFM). PUs may be configured as Central Processors (CP), Integrated Firmware Processors (IFP), Integrated Facility for Linux (IFL), Integrated Information Processors (zIIP), Internal Coupling Facility (ICF) processors, System Assist Processors (SAP), or designated spares. The IBM Z architecture strongly emphasizes pervasive encryption through extensive hardware-accelerated cryptographic functions including AES, DES, TDES, SHA algorithms, and a built-in random number generator.

IBM z13

Debuted on January 13, 2015, the z13 operates with an 8-core z13 processor clocked at 5 GHz. This system can accommodate up to 168 Processing Unit (PU) cores, with 141 available for client workload configuration and a maximum of 10.144 TiB of redundant array of independent memory (RAIM). Processing Units may be designated as Central Processors (CP), Integrated Firmware Processors (IFP), Integrated Facility for Linux (IFL) processors, z Integrated Information Processors (zIIP), Internal Coupling Facility (ICF) processors, System Assist Processors (SAP), or reserved as spares. The zApplication Assist Processor (zAAP) capabilities are incorporated within the zIIP on the z13.

The z Systems z13s (2965 series), launched on February 17, 2016, incorporates a novel vector architecture and is among the final models to maintain support for operating systems running in ESA/390 architecture mode.

IBM zEnterprise System

This series includes two distinct generations: the initial one from 2010/2011 offering single-rack ("business class") and dual-rack ("enterprise class") configurations; followed by the second generation in 2012/2013, known as generation 12, which includes the single-rack zBC12 and dual-rack zEC12 models.

zEnterprise gen2 (zBC12 and zEC12)

On April 8, 2014, IBM introduced the IBM Enterprise Cloud System—a unified infrastructure solution combining mainframe hardware, software, and storage components. Designed to rival solutions from VCE, HP, and Oracle, it can host up to 6,000 virtual machines within a single physical footprint.

In June 2014, IBM delivered its inaugural Enterprise Cloud System to Vissensa, a managed service provider based in the United Kingdom.

zEnterprise Business Class 12 (zBC12) – Released in July 2013 as an entry-level single-rack platform aimed at medium-sized enterprises. Offered in two variants—H06 and H13—the zBC12 supports Linux virtualization through its Enterprise Linux Server edition running on the z/VM hypervisor. The H13 model contains 18 processor cores with up to 13 configurable; the H06 includes nine cores with six configurable. It also facilitates connectivity to the zBX expansion chassis.

zBC12 configurations
Model	CPs	IFLs	zAAPs / zIIPs	ICFs	SAPs	IFPs	Spares	zBX	Memory (GB)
H06	0–6	0–6	0–4 / 0–4	0–6	2	1	0	0–1	8–240
H13	0–6	0–13	0–8 / 0–8	0–13	2	1	2	0–1	16–496

zEnterprise Enterprise Class 12 (zEC12) – A premium dual-rack mainframe unveiled in August 2012 featuring five hardware options (H20, H43, H66, H89, HA1). It is built around the 5.5 GHz 8-core zEC12 processor supporting out-of-order execution and CISC architecture. The system accommodates up to 120 cores with 101 configurable for client workloads. Each core can be assigned roles such as CP, IFL, zAAP, zIIP, ICF, or SAP. RAIM capacity reaches up to 3 TB.

zEC12 configurations
Model	CPs	IFLs	zAAPs / zIIPs	ICFs	SAPs	IFPs	Spares	Memory (GB)
H20	1–20	0–20	0–10 / 0–10	0–20	4–8	1	2–20	32–704
H43	1–43	0–43	0–21 / 0–21	0–43	8–16	1	2–43	32–1392
H66	1–66	0–66	0–33 / 0–33	0–66	12–24	1	2–66	32–2272
H89	1–89	0–89	0–44 / 0–44	0–89	16–32	1	2–89	32–3040
HA1	1–101	0–101	0–50 / 0–50	0–101	16–32	1	2–101	32–3040

The EC12 provides a total capacity increase of approximately 50% over its predecessor—reaching up to 78,000 MIPS—and supports transaction processing along with Flash Express technology that integrates SSDs to boost paging and input/output efficiency.

zEnterprise gen1 (114 and 196)

Introduced in July 2010, the zEnterprise platform featuring the z196 model combines mainframe and distributed server technologies. It consists of three key parts:

System z mainframe server
IBM zEnterprise BladeCenter Extension (zBX)
IBM zEnterprise Unified Resource Manager (zManager), which provides centralized control over all components

The zEnterprise system enhances traditional mainframe strengths—such as efficient management, flexible resource allocation, and improved maintainability—to support workloads running on AIX with POWER7, Windows, or Linux on x86 architectures.

The zBX integrates IBM BladeCenter servers and workload accelerators under unified mainframe management. It connects to the central processing complex via a high-speed private network, reducing the need for additional networking equipment while improving security.

Unified Resource Manager virtualizes resources from both System z and the zBX, delivering consolidated management capabilities, dynamic resource redistribution to prevent downtime, energy consumption tracking, security controls, and virtual networking through a single interface.

zEnterprise 114 – Released in July 2011 as an entry-level single-rack system with two variants (M05 and M10), the z114 targets medium-sized enterprises. It supports up to 14 cores (10 configurable) running at 3.8 GHz, is compatible with both the zBX and Unified Resource Manager, and occupies approximately half the footprint of the z196. This model offers 130 capacity options with lower power consumption and cost while preserving hybrid system functionality.

z114 models
Model	CPs	IFLs	zAAPs / zIIPs	ICFs	SAPs	Spares	zBX	Memory (GB)
M05	0–5	0–5	0–2 / 0–2	0–5	2–4	0	0–1	8–120
M10	0–5	0–10	0–5 / 0–5	0–10	2–4	2	0–1	16–248

Each core within the system can be designated as a Central Processor (CP), Integrated Facility for Linux (IFL), z Application Assist Processor (zAAP), zIIP, Internal Coupling Facility (ICF), or System Assist Processor (SAP). The z114 supports up to 248 GB of redundant array of independent memory (RAIM).

zEnterprise 196 – The top-tier dual-rack z196 is available in five hardware configurations: M15, M32, M49, M66, and M80. The model numbers indicate the count of customer-available workload cores; additional cores are allocated as spares or SAPs.

z196 models
Model	CPs	IFLs	zAAPs / zIIPs	ICFs	SAPs	Spares	zBX	Memory (GB)
M15	0–15	0–15	0–7 / 0–7	0–15	3	2–15	0–1	32–752
M32	0–32	0–32	0–16 / 0–16	0–16	6	2–32	0–1	32–1520
M49	0–49	0–49	0–24 / 0–24	0–16	9	2–49	0–1	32–2288
M66	0–66	0–66	0–33 / 0–33	0–16	12	2–66	0–1	32–3056
M80	0–80	0–80	0–40 / 0–40	0–16	14	2–80	0–1	32–3056

Powered by the z196 microprocessor—a quad-core out-of-order CISC processor clocked at 5.2 GHz—the platform can accommodate up to 24 processors totaling 96 cores, with 80 cores accessible for operating systems and application workloads. Similar to the z114, each core may be configured as CP, IFL, zAAP, zIIP, ICF, or SAP. The system supports x86 or Power ISA blades through the zBX extension. The maximum usable RAIM memory reaches up to 3 TB.

When compared to its predecessor, the z10, the z196 doubles memory capacity and increases total throughput by approximately 60% (up to 52 GIPS). It also incorporates support for both the BladeCenter Extension (zBX) and Unified Resource Manager.

IBM System z10

The IBM System z10 series enhanced memory capacity and supported up to 64 central processors (CPs) within a single frame. Its processor, operating at full speed, achieved up to 62% greater uniprocessor performance compared to the z9, enabling:

A 50% increase in performance and a 70% boost in usable capacity through a 4.4 GHz processor tailored for CPU-heavy tasks and extensive server consolidation.
Dynamic capacity management using Capacity Provisioning alongside Workload Manager (WLM), which facilitates automatic or manual temporary capacity adjustments in response to workload variations.

Prominent models include:

z10 Business Class (2098 series), released on October 21, 2008
z10 Enterprise Class (2097 series), introduced on February 26, 2008

IBM System z9

Launched in 2005, the IBM System z9 lineup comprised the Enterprise Class (z9 EC) and Business Class (z9 BC) servers, featuring:

Increased adaptability in configuring general purpose processor (CP) capacity, with the z9 EC offering four sub-capacity levels for setups with eight or fewer CPs.
Incorporation of zIIP processors designed to offload eligible workloads from general purpose processors, enhancing overall system throughput.
MIDAW (Modified Indirect Data Address Word) technology to improve channel utilization and I/O response times for native FICON applications utilizing extended format datasets such as DB2 and VSAM.
CP Assist for Cryptographic Functions (CPACF) implemented across all CP and IFL processors supporting clear key encryption, with upgraded support for AES-128, SHA-256, DES, Triple DES, and SHA-1 algorithms.

Key models include:

z9 Business Class (2096 series), succeeding the z890 and smaller z990 variants (released in 2006)
z9 Enterprise Class (2094 series), introduced as the first z9-109 model in 2005

IBM zSeries family

The eServer zSeries 900 (z900), announced in October 2000 and commercially available by December of that year, marked IBM's initial implementation of the 64-bit z/Architecture extension of the S/360 architecture while retaining compatibility with legacy 31-bit and 24-bit addressing software.

Equipped with either 12 or 20 "Blue Flame" processors—up to 16 of which could be active as Central Processors—these were integrated into a multi-chip module featuring 101 glass-ceramic layers and 4226 I/O pins. Each processor contained approximately 47 million transistors on a die size of 177 mm². Compared to its predecessor, Blue Flame doubled the Level 1 cache (divided as 256 KB instruction + 256 KB data) and expanded Level 2 cache to 32 MB. Peripheral I/O throughput tripled to 24 GB/s, while main memory bandwidth reached 70 GB/s with support for up to 64 GB. Initially clocked at 769 MHz using a 180 nm fabrication process, it later achieved speeds of up to 917 MHz on silicon-on-insulator technology by May 2002, consuming approximately 38 Watts.

In 2002, IBM released the z800, an entry-level mainframe featuring five Blue Flame processors running at 625 MHz (with up to four active as Central Processors) sharing an 8 MB Level 2 cache. It provided an I/O bandwidth of 6 GB/s and supported memory capacities up to 32 GB.

The z990, redesigned for mid- to high-end use cases and launched throughout mid to late 2003, introduced IBM's first superscalar CMOS mainframe processors—a dual-core chip containing approximately 121 million transistors on a die measuring 266 mm², fabricated using a 130 nm process and consuming about 55 Watts at a clock speed of 1.2 GHz. Each core was equipped with a cryptographic coprocessor supporting DES and SHA-1 algorithms. The z990 scaled up to a maximum of 48 cores (with up to 32 enabled as Central Processors) and incorporated non-uniform memory access (NUMA) architecture by grouping processors and memory into as many as four "book"-modules, each featuring a dedicated 32 MB Level 2 cache. This model was also IBM’s first mainframe capable of speculative memory disambiguation.

The system quadrupled maximum I/O bandwidth to reach 96 GB/s and increased memory capacity up to 256 GB. It expanded I/O channels through quad-Logical Channel SubSystems (LCSS), with each operating system instance restricted to one LCSS supporting up to 256 channels. Logical partitions doubled in number to a maximum of thirty, while Parallel Sysplex distance extended out to approximately 100 km. Full operating system support for all processors was phased in over several years: z/OS supported up to twenty-four processors by September 2004 and expanded this support to thirty-two by June 2005; z/VM added compatibility with thirty-two processors by June 2007.

In May of 2004, the z890 succeeded the z800 model. It maintained similar memory capacity and core counts but upgraded processors by adopting those used in the z990 at a reduced clock rate of one gigahertz. The system featured a Level 2 cache of thirty-two megabytes and supported two LCSSs delivering sixteen gigabytes per second in I/O bandwidth.

Also during 2004, IBM broadened its lower-cost restricted processor offerings—initially launched with Integrated Facility for Linux (IFL) dedicated solely to Linux workloads—to include the z Application Assist Processor (zAAP), designed specifically for Java and XML processing tasks. Both IFLs and zAAPs are physically identical to Central Processors but benefit from reduced software licensing costs. In addition, IBM introduced the z Integrated Information Processor within the System z9 family in 2006 as another specialized processor category.

Processors and memory

IBM zSeries machines incorporate z/Architecture microprocessors—multi-core, out-of-order, CISC-based chips. The maximum core count for each zEC12 variant is reflected in its model designation; for instance, the H20 model provides up to 20 cores available to customers, along with additional spare and System Assist Processor (SAP) cores. Each core functions as a Central Processor (CP), Integrated Facility for Linux (IFL), z Application Assist Processor (zAAP), z10 Integrated Information Processor (zIIP), Internal Coupling Facility (ICF), or SAP.

Processor book

A processor book is a modular component within IBM mainframes that houses processors, memory modules, and input/output interfaces. In the z196 system, a multi-chip module is affixed to each processor book to boost performance capabilities.

Computing power acquisition

Contemporary IBM Z mainframes are generally acquired through leasing or service-oriented contracts. Clients lease workload capacity and can enable extra features by paying additional fees, reflecting a flexible, consumption-based procurement approach.

Operating systems

Systems such as the z15, z14, z13, zEC12, zBC12, z114, and z196 are compatible with IBM operating systems like z/OS, z/VM, z/VSE, and z/TPF. They also support Linux variants including Red Hat Enterprise Linux 6 and SUSE Linux Enterprise Server 11. Since 2011, IBM has incorporated support for Microsoft Windows Server 2008 through x86 blade servers housed within the zEnterprise BladeCenter Extension (zBX), which also accommodates IBM WebSphere DataPower Integrated Appliance XI50 for advanced enterprise application integration.

BladeCenter Extension (zBX)

The optional zEnterprise BladeCenter Extension (zBX) within the zEnterprise System provides redundant top-of-rack network switches, power supplies, additional cooling blowers, and an IBM BladeCenter chassis. This extension allows direct integration and management of POWER7 and x86 blade servers from the mainframe environment. A prominent hybrid mainframe deployment is the gameframe system used by Hoplon Infotainment.

Supporting up to 112 blade modules, the zBX connects to the System Z server via a redundant and secure private network based on 10 Gigabit Ethernet, supplemented by a separate 1 Gigabit Ethernet management connection.

Unified Resource Manager

The zEnterprise Unified Resource Manager (also known as zManager) virtualizes compatible zBX platforms into a cohesive system to simplify administration. It manages workload prioritization, detects performance bottlenecks or faults, and dynamically reallocates resources to ensure compliance with defined quality of service standards, thereby improving operational effectiveness.

Liquid cooling

The zEC12 and z196 models offer an optional external liquid cooling solution using water-cooled heat exchangers to enhance thermal regulation in data center settings.

PU characterization

Processor units (PUs) are categorized according to their roles:

CP: Central processors handling general-purpose workloads across supported operating systems.
IFL: Integrated Facility for Linux processors dedicated exclusively to Linux and z/VM workloads; capable only of booting Linux or z/VM.
zAAP: Z Application Assist Processor designed for specific z/OS applications such as IBM JVM and XML processing; from the z13 model onward, integrated with zIIP processors.
zIIP: Integrated Information Processor supporting designated z/OS functions including XML services, IPSec offloading, IBM DB2 DRDA components, and financial reporting tasks.
ICF: Internal Coupling Facility processors running Coupling Facility Control Code essential for clustering in z/OS environments.
SAP: System Assist Processor responsible for managing input/output operations.
IFP: Integrated Firmware Processor introduced with the zEC12/zBC12 models to manage new PCIe adapters.
Spares: processors reserved as failover units in case of failure of any PU type.

Workloads eligible for execution on zAAP processors may alternatively run on zIIPs if no zAAPs are installed. IBM does not levy software licensing charges on workloads executed on either zAAP or zIIP processors.

Adding IFLs, zAAPs, zIIPs, ICFs, SAPs, or IFPs does not influence overall system capacity or its rating in terms of MSUs—only CPs contribute to capacity measurement.

External links

IBM eServer zSeries		IBM System z9 Template:Br2005/2006	IBM System z10Template:Br2008	IBM zEnterprise		IBM z13Template:Br2015/2016	IBM z14Template:Br2017/2018	IBM z15Template:Br2019/2020
z800, z900Template:Br2000/2002	z890, z990Template:Br2003/2004			z114, z196Template:Br2010/2011	zBC12, zEC12Template:Br2012/2013