Preview: IBM z/VM 7.3

IBM Canada Announcement A22-0160
April 5, 2022

Table of contents
OverviewOverviewProduct positioningProduct positioning
Key requirementsKey requirementsStatement of general directionStatement of general direction
Planned availability datePlanned availability dateRegional availabilityRegional availability

At a glance

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IBM® z/VM®, the leading platform virtualization product for IBM Z® and IBM LinuxONE servers, will be updated in version 7.3 to provide:

  • An increase in the maximum size of a Single System Image (SSI) cluster from four members to eight, enabling clients to grow their SSI clusters to allow for more workload and reduce the proportion of spare capacity space required to accommodate planned system outages
  • Enablement to allow Non-Volatile Memory Express (NVMe) solid-state drive (SSD) adapters to be accessed as one or more EDEVICEs, taking advantage of the capacity and performance benefits these devices offer on LinuxONE
  • A new Architecture Level Set (ALS) that requires one of the following IBM Z servers:
    • IBM z16 (all models)
    • IBM z15™ (all models)
    • IBM z14® (all models)
    • IBM LinuxONE III (all models, including LinuxONE III Express)
    • IBM LinuxONE II Emperor
    • IBM LinuxONE II Rockhopper
  • Timely, client-driven functions previously delivered in the service stream of z/VM 7.2

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Top rule

z/VM 7.3 will provide IBM clients with the premier hypervisor on their modernization to hybrid cloud for hosting enterprise-class virtual servers to exploit the IBM Z and LinuxONE advantages in scalability, performance, high availability, and security.

The objective of z/VM 7.3 is to enhance the proof points on their modernization to hybrid cloud, specifically those associated with scalability and efficiency. z/VM is designed to enable the deployment of up to thousands of Linux® servers on a single IBM Z or LinuxONE server.

While cloud computing has become the standard use model for IT services, an IT infrastructure continues to be the foundation of every IT service. Realizing the benefits of cloud computing requires an infrastructure such as z/VM that delivers availability, reliability, security, and performance, while also providing strong virtualization technology.

Virtualization is fundamental to delivering infrastructure as a service (IaaS), the basic building block for cloud. IBM continues to invest in z/VM technology to provide leading-edge virtualization capabilities. This progression can meet the needs of IT organizations to deliver the foundation for user satisfaction on both types of workloads:

  • Cloud-native workloads based on Red Hat® OpenShift® Container Platform and IBM Cloud® Paks or other container technologies
  • Noncontainerized workloads deployed in a cloud or traditional environment from IBM such as IBM WebSphere®, open source such as MongoDB, or software from ISVs

z/VM, together with IBM Cloud Infrastructure Center that helps to manage the lifecycle of virtual infrastructure, provides the foundation for private cloud on an IBM Z and LinuxONE server as part of a hybrid cloud approach.

z/VM virtualization technology enables the deployment of more virtual servers, for both noncontainerized and cloud-native workloads, in a single IBM Z or LinuxONE server than any other platform through legendary scalability, system management, and performance. z/VM supports the following guest operating systems: Linux, IBM z/OS®, IBM z/VSE®, IBM z/TPF, and z/VM itself, as well as Red Hat Enterprise Linux CoreOS as a part of the Red Hat OpenShift Container Platform. In addition, the z/VM hypervisor helps ensure continuous infrastructure availability by tightly integrating with IBM GDPS® resiliency-focused offerings and Live Guest Relocation support.

With z/VM 7.3, IBM continues to deliver enhancements to its z/VM advanced virtualization technology on IBM Z and LinuxONE servers using the z/VM continuous delivery (CD) model. This CD model for new function offers clients timely support for new technology throughout the life of a z/VM product release using a delivery mechanism that is familiar to clients and time tested. The z/VM CD model allows schedule flexibility as IBM partners with the z/VM community in the design, development, and delivery of new functions that are not centred around a specific release date.

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Key requirements

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Operating environment

z/VM V7.3 is planned to support the following IBM Z servers:

  • IBM z16 (all models)
  • IBM z15 (all models)
  • IBM z14 (all models)
  • IBM LinuxONE III (all models, including LinuxONE III Express)
  • IBM LinuxONE II Emperor
  • IBM LinuxONE II Rockhopper

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Planned availability date

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Third quarter, 2022

Previews provide insight into IBM plans and direction. Availability, prices, ordering information, and terms and conditions will be provided when the product is announced.

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Top rule

The following enhancements are included in z/VM 7.3:

  • 8-member SSI support. Increases the maximum size of a Single System Image (SSI) cluster from four members to eight, enabling clients to grow their Single System Image (SSI) clusters to allow for more workload and providing more flexibility to use live guest relocation (LGR) for nondisruptive upgrades and workload balancing.
  • NVMe emulated device (EDEVICE) support. Enables NVMe devices connected through PCI Express (PCIe) adapters to be defined and managed as Fixed-Block Architecture (FBA) EDEVICEs. As such, all host and guest FBA functions are supported except for those that require stand-alone support such as Warm Start and Checkpoint. Linux guests exploiting EDEVICEs defined on NVMe adapters are not eligible for LGR. NVMe Adapters are only available on LinuxONE servers.
  • Up to 4 TB of memory per LPAR. This new function was delivered in the service stream of z/VM 7.2. A fully configured 8-member SSI can address up to 32 TB on a single IBM Z or LinuxONE server, or 32 TB across multiple servers along with up to 80 logical processors (40 when Simultaneous Multi-Threading (SMT) is enabled) supported on each member.
  • Dynamic Memory Downgrade. This new function was delivered in the z/VM 7.2 service stream, and it provides the added flexibility of moving LPAR memory from one or more z/VM system images to one or more other z/VM system images running on the same physical server. This can help clients to nondisruptively align their hardware assets with shifting workload demands across their z/VM system images if they are in an SSI cluster or in separate z/VM LPARs. This may prove particularly useful when moving running virtual machines from one SSI member to another using LGR.
  • New Architecture Level Set (ALS). z/VM 7.3 includes an ALS that requires an z14 server and higher.
  • External Security Manager interface enhancements. These interfaces have been enhanced to allow control of the CP DEFINE MDISK command. These interfaces are exploited by IBM RACF®/VM and enable a z/VM security administrator to restrict and audit all means of creating a minidisk.
  • System default changes:
    • Default password for User Directory

      New with product install, z/VM 7.3 provides the ability to select a default password when installing or upgrading a z/VM system.

    • User Directory TODENABLE

      Some capabilities that previously required OPTION TODENABLE in the user's directory definition will be standard for all users in z/VM 7.3. Specifically, all virtual machines on z/VM 7.3 will be able to alter their virtual time-of-day (TOD) clocks using the SET CLOCK instruction. In addition, class G users no longer need TODENABLE to set the virtual clock to a specified value using the SET VTOD command with the DATE, TIME, and SYSTEM options. TODENABLE is still required for the FROMUSER and MSGPROC options of SET VTOD, which involve access to another virtual machine's clock.

    • TCP/IP configuration statement changes

      In z/VM 7.3, the NOUDPQUEUELIMIT option of the ASSORTEDPARMS statement is being replaced by a new UDPQUEUELIMIT configuration statement. This new statement will allow a numerical limit to be specified for the maximum number of incoming datagrams queued on a UDP port. The default limit is 20 datagrams. If 0 is specified, there will be no limit, which is the equivalent of NOUDPQUEUELIMIT. The NOUDPQUEUELIMIT option will still be accepted in z/VM 7.3 but UDPQUEUELIMIT takes precedence. In addition, the FOREIGNIPCONLIMIT default will be changed to a set value of 256 and will no longer be based on the initial TCBPOOLSIZE.

    • Change in location and size of the MONDCSS and PERFOUT saved segments

      The default CP MONITOR MONDCSS saved segment starting virtual address has been changed to 1 GB and the size has been increased to 96 MB. The IBM Performance Toolkit PERFOUT saved segment starting virtual address has been changed to 1120 MB, immediately following the new MONDCSS. The reasons for these changes include:

      • Moving the segment starting locations addresses a problem with the Linux kdump configuration, which failed in a virtual machine with 1 GB of virtual memory that had attached one or both current versions of these segments.
      • Increasing the size of the MONDCSS segment accommodates the increased volume of CP Monitor data produced and provides room for its future growth.

        These changes will not affect existing versions of these segments; they must be re-created for the new defaults to take effect.

  • Support for the IBM z16 Model A01 servers includes:
    • Guest enablement to exploit the following functions:
      • Imbedded Artificial Intelligence Acceleration is designed to reduce the overall time required to execute CPU operations for neural networking processing functions and help support real-time applications like fraud detection.
      • Compliance-ready Central Processor Assist for Cryptographic Functions (CPACF) counters support allows guests to track crypto compliance and instruction usage.
      • Breaking Event Address Register (BEAR) enhancement facility improves the ability to debug wild branches.
      • Vector Packed Decimal Enhancements 2 delivers new instructions intended to provide performance improvements.
      • Reset DAT Protection Facility provides a more efficient way to disable DAT protection, such as during copy-on-write or page change tracking operations.
      • Support for the Consolidated Boot Loader provides guest IPL from a SCSI LUN.

        Note: Guest IPL from SCSI, with or without the DUMP option, will now require a minimum guest virtual memory size of 768 MB.

      • The RoCE Express3 adapter allows guests to exploit Routable RoCE, Zero Touch RoCE, and SMC-R V2 support.
      • The Crypto Express8S (CEX8S) adapter is supported as a dedicated or shared resource. Dedicated guests will be able to take advantage of all functionality available with the CEX8S adapters, including assorted new enhancements and use of Quantum Safe APIs.
    • Support for CPU and Core topology location information will be included in z/VM monitor data, providing a better picture of the system for diagnostic and tuning purposes.

    This support is available for z/VM 7.1 and 7.2 with the PTF for APAR VM66532.

  • The following infrastructure support must be installed on all members within a z/VM SSI cluster before any member of the cluster is IPLed on an IBM z16 server:
    • z/VM 7.3
    • z/VM 7.2 with the PTF for APAR VM66504
    • z/VM 7.1 with the PTFs for APARs VM66206 and VM66504

    For further information about z/VM support of the IBM z16 server, see the z/VM IBM z16 required service web page and the IBM Support - Preventive Service Planning bucket Upgrade 3911DEVICE, Subset 3911/ZVM .

    For additional information about the IBM z16 capabilities, see the hardware announcements for these servers in the Reference information section.

  • z/VM CD model

    IBM will deliver most new z/VM 7.3 function as new function APARs in the service stream. When z/VM 7.3 becomes available, z/VM 7.2 will, with a few exceptions, receive only corrective service. Similarly, when a new release is introduced after z/VM 7.3, new function APARs will be delivered on that release and 7.3 will receive mostly corrective service only. For additional information about the z/VM CD model, see the z/VM 7.1 Software Announcement A18-0477, dated August 7, 2018.

The following z/VM 7.2 enhancements delivered during 2021 will be in the base of z/VM 7.3, providing additional IBM z16 benefit for z/VM workloads:

  • 4 TB Real Memory support. With the PTF for APAR VM66173, support for up to 4 TB of real memory will allow z/VM systems to address a full 4 TB of first-level (real) memory, doubling the previous supported limit of 2 TB.
  • Dynamic Memory Downgrade support. With the PTF for APAR VM66271, Dynamic Memory Downgrade extends the real storage dynamic management characteristics of z/VM by allowing up to 50% of the real memory to be removed from a running z/VM system. A minimum hardware bundle level is required to avoid a possible downgrade stall. For additional details, see the Dynamic Memory Downgrade information web page.
  • Improved LGR for shared crypto users. With the PTF for APAR VM66496, LGR for APVIRT shared crypto environments is enabled when the type of shared crypto resource on the source system does not match the type on the target system.
  • z/Architecture® Extended Configuration (z/XC) support. With the PTFs for APARs VM66201 (CP), VM66425 (CMS), and VM66489 (Performance Toolkit), CMS applications that run in IBM z/Architecture can use multiple address spaces. Programs can use z/Architecture instructions and registers, within the limits of z/CMS support, and can use VM data spaces in the same CMS session. IBM z16 requires z/CMS and z/XC support to be configured within guest virtual machines that exploit z/VM HCD support. In addition, when the PTF for IOCP APAR VM66549 is applied, z/CMS support is required to be configured on any IBM Z or LinuxONE server. IOCP support is in the base of z/VM 7.3 and requires z/CMS.
  • Direct to Host Service Download support. With the PTF for APAR VM66540, z/VM 7.2 provides an optional way to download service to your z/VM system. A web interface simplifies the downloading of z/VM service that was ordered through IBM Shopz. The service files can be transferred through direct-to-host connection.

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Product positioning

Top rule

z/VM is the leading platform virtualization product for IBM Z and LinuxONE servers and was built on and expanded from the fundamentals of virtualization to help optimize IT environments.

Virtualization is the entry point to build flexible and cost-effective cloud environments that can differentiate service delivery to provide an enhanced client experience. In essence, it can become a key control point in the service delivery value chain. The ultimate choice of hypervisor and its management capabilities heavily influences follow-on decisions about products that are selected to support implementations of cloud. The objective is to continue to provide a launching point with z/VM for a new technology base and a deployment and consolidation platform for Linux and Red Hat OpenShift.

The IBM objective is to expand the penetration of z/VM in the existing IBM Z install base and attract new clients to the platform with offerings such as LinuxONE. To accomplish this, z/VM 7.3 offers improvements that can help provide a competitive advantage or eliminate a competitive gap.

With z/VM, together with IBM Cloud Paks based on Red Hat OpenShift and additional container technologies based on Linux, IBM Z, and LinuxONE provide a highly scalable, secure, and efficient on-premises private cloud infrastructure.

z/VM 7.3 can help extend the business value of IBM Z and LinuxONE technology across the enterprise by integrating applications and data, while providing exceptional levels of availability, security, and operational ease. This applies not only for private cloud deployments of containerized and noncontainerized workloads, which can be part of a client's hybrid cloud approach, but also for what is often called "traditional IT". World-class virtualization technology that is offered by z/VM can provide the ability to host large numbers of virtual servers running different operating systems on IBM Z and virtual Linux servers running on LinuxONE.

Typical workload scenarios are the new/additional deployment and large consolidation of:

  • Cloud-native workloads based on Red Hat OpenShift and IBM Cloud Paks or other container technologies
  • Noncontainerized workloads that require great throughput, such as IBM Db2® Warehouse, IBM Db2 LUW, Oracle database, MongoDB, PostgreSQL, or others
  • Noncontainerized applications deployments, such as those based on WebSphere, ISV applications like SAP, and others, which include open source

Because virtualization is the entry point to cloud, the hypervisor choice that clients make heavily influences their implementations of cloud throughout the stack. IBM's strategic objective is to continue to offer IBM Z and LinuxONE servers as the core of trusted digital experiences, and together with z/VM as part of IBM's open hybrid cloud approach, as well as for large-scale Linux deployments. To accomplish this, IBM will continue to make changes and improvements to z/VM that provide competitive advantages or eliminate competitive gaps.

To help ensure data-at-rest and in-flight stay safe and secure, z/VM supports the use of the IBM Full Disk Encryption (FDE) feature of the IBM DS8000® and Endpoint Security of the IBM DS8900. z/VM also supports the ability of guests to use encrypted tape and supports encrypted paging. Ciphering will occur as data move between active memory and a paging volume owned by the CP hypervisor. Encrypted paging can be enabled and disabled dynamically.

The TCP/IP for z/VM TLS/SSL server facilitates security-rich and private conversations between z/VM servers and external clients. With z/VM support for TLS 1.2 and SHA-2 hashing, a z/VM server can use industry-standard cryptographic protocols in a FIPS 140-2 compliant mode to communicate securely with a client without a change to the server itself.

z/VM enables Crypto Express features, which are tamper-resistant cryptographic coprocessors, available to guests with either dedicated access, for use in both secure-key or clear-key operations, or shared access for clear-key operations. z/VM can virtualize IBM Z cryptographic devices so they can be shared by many Linux systems and supports the IBM z16, z15, and z14 limit of more than 16 Crypto Express feature domains. With shared access, z/VM can also balance the workload across multiple cryptographic devices. Should one device fail or be brought offline, z/VM can transparently shift Linux systems using that device to an alternate one without user intervention.

The z/VM environment is further extended with dynamic crypto support, enabling changes to the Adjunct Processor (AP) Cryptographic (crypto) environment on a z/VM system dynamically and, allowing the addition, removal, or reassignment of crypto hardware to be less disruptive to the system and its guests.

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Statement of general direction

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Withdrawal of support for TCP/IP LAN Channel Station (LCS) devices

Many IBM Z clients continue to rely on Systems Network Architecture (SNA) applications for mission-critical workloads, and IBM has no plans to discontinue support of the SNA protocol, including the SNA APIs.

As stated in Hardware Announcement A22-0010, dated April 5, 2022, IBM z16 is planned to be the last IBM Z server to support the OSE CHPID type, which enables the host to send and receive native SNA-format Ethernet frames using the OSA Express 1000Base-T adapters. z/VM systems that rely on VTAM® and utilize External Communications Adapter (XCA) major nodes as the transport should be updated to utilize Channel-to-Channel connections to z/OS so that Enterprise Extender or some other form of SNA-over-IP technology can be used. The OSE chpid type also is used to provide LAN Channel Station (LCS) emulation. With its withdrawal, IBM intends z/VM 7.3 to be the last z/VM release to provide TCP/IP support for the LCS device driver.

z/CMS as the default CMS

z/VM 7.3 is planned to be the last z/VM release planned to have ESA/390 CMS as the default. A future z/VM release will use z/CMS, renamed "CMS", as the default. ESA/390 CMS, renamed "CMS390", is planned to be available for guests that are dependent on ESA/390 or 370 accommodation.

Statements by IBM regarding its plans, directions, and intent are subject to change or withdrawal without notice at the sole discretion of IBM. Information regarding potential future products is intended to outline general product direction and should not be relied on in making a purchasing decision. The information mentioned regarding potential future products is not a commitment, promise, or legal obligation to deliver any material, code, or functionality. Information about potential future products may not be incorporated into any contract. The development, release, and timing of any future features or functionality described for IBM products remain at the sole discretion of IBM.

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Reference information

Top rule

For information about z/VM 7.2, see:

  • Software Announcement A20-0486, dated August 4, 2020
  • Software Announcement A20-0140, dated April 14, 2020

For information about z/VM 7.1, see:

  • Software Announcement A18-0805, dated October 16, 2018
  • Software Announcement A18-0477, dated August 7, 2018
  • Software Announcement A18-0230, dated April 10, 2018

For information about IBM Cloud Infrastructure Center, see:

  • Software Announcement A22-0191, dated March 1, 2022
  • Software Announcement A21-0437, dated August 3, 2021
  • Software Announcement A21-0095, dated February 16, 2021
  • Software Announcement A20-0596, dated October 6, 2020
  • Software Announcement A20-0215, dated April 14, 2020
  • Software Announcement A19-0785, dated December 3, 2019

For information about IBM z/VSE V6.2, see Software Announcement A20-0185, dated April 14, 2020.

For information about the IBM z16, see Hardware Announcement A22-0010, dated April 5, 2022.

For information about the z15, see:

  • Hardware Announcement A20-0050, dated April 14, 2020
  • Hardware Announcement A20-0075, dated January 14, 2020
  • Hardware Announcement A19-0846, dated November 26, 2019
  • Hardware Announcement A19-0283, dated September 12, 2019

For information about the LinuxONE III, see:

  • Hardware Announcement A20-0076, dated April 14, 2020
  • Hardware Announcement A20-0075, dated January 14, 2020
  • Hardware Announcement A19-0225, dated September 12, 2019

For information about the z14 Model ZR1, see Hardware Announcement A18-0133, dated April 10, 2018.

For information about the LinuxONE Rockhopper II, see Hardware Announcement A18-0138, dated April 10, 2018.

For information about the z14, see:

  • Hardware Announcement A17-0866, dated November 28, 2017
  • Hardware Announcement A17-0392, dated July 17, 2017

For information about the Emperor II, see:

  • Hardware Announcement A17-0866, dated November 28, 2017
  • Hardware Announcement A17-0572, dated September 12, 2017

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Statement of good security practices

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IT system security involves protecting systems and information through prevention, detection, and response to improper access from within and outside your enterprise. Improper access can result in information being altered, destroyed, or misappropriated or can result in misuse of your systems to attack others. Without a comprehensive approach to security, no IT system or product should be considered completely secure and no single product or security measure can be completely effective in preventing improper access. IBM systems and products are designed to be part of a comprehensive security approach, which will necessarily involve additional operational procedures, and may require other systems, products, or services to be most effective. IBM does not warrant that systems and products are immune from the malicious or illegal conduct of any party.

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Regional availability

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Anguilla, Antigua and Barbuda, Aruba, Bahamas, Barbados, Bermuda, Sint Eustatius and Saba Bonaire, Canada, Cayman Islands, Curacao, Dominica, Grenada, Guyana, Jamaica, Montserrat, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Sint Maarten, Suriname, Trinidad and Tobago, Turks and Caicos Islands, and British Virgin Islands


z15 is a trade-mark of IBM Corporation in the United States, other countries, or both.

IBM, z/VM, IBM Z, IBM z14, IBM Cloud, WebSphere, z/OS, z/VSE, GDPS, RACF, z/Architecture, Db2, DS8000 and VTAM are registered trade-marks of IBM Corporation in the United States, other countries, or both.

The registered trade-mark Linux® is used pursuant to a sublicense from the Linux Foundation, the exclusive licensee of Linus Torvalds, owner of the mark on a world­wide basis.

Red Hat and OpenShift are registered trade-marks of Red Hat Inc. in the U.S. and other countries.

Other company, product, and service names may be trade-marks or service marks of others.

tm Trade-mark owned by International Business Machines Corporation and is used under license by IBM Canada Ltd.

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(**) Company, product or service name may be a trade-mark or service mark of others.

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