When considering IBM System z Operating Systems, typically z/OS is considered to be the flagship product, delivering best-of-breed features, including but not limited to, performance, reliability, availability, security, capacity, et al.  Therefore it easy to overlook the flexible virtualization capabilities of z/VM, delivering the architectural foundation for the increasingly attractive LinuxONE offering.  Quite simply, the fundamental strength of z/VM is an ability for hundreds if not thousands of virtual machines to share system resources with high levels of resource utilization.  The recent release of z/VM V6.4 provides even greater levels of scalability, security, resource optimization and efficiency to create opportunities for cost savings, while providing a robust foundation for cloud computing on z Systems servers.

Major technical highlights of z/VM 6.4 include:

• Simultaneous MultiThreading (SMT) technology extends per-processor, core capacity growth beyond single-thread performance for Linux on z Systems running on an IBM Integrated Facility for Linux (IFL) specialty engine on a z13, z13s or LinuxONE server.
• Enhanced Real & Guest Virtual Memory Support. The maximum amount of real storage supported by z/VM increases from 1 to 2 TB, whereas maximum supported virtual memory for a single guest remains at 1 TB.  Maintaining the virtual to real memory allocation, doubling the real memory used, results in doubling the active virtual memory that can be used effectively.  This virtual memory can be sourced from an increased number of virtual machines and/or larger virtual machines, delivering greater leverage of white space.
• Surplus CPU Power Distribution Improvement. Virtual machines not utilizing all of their entitled CPU power, determined by their share setting, generate “surplus CPU power.”  This surplus CPU resource can be distributed to other virtual machines in proportion to their share settings, managed independently across virtual machines for each processor type, namely General Purpose (GP), zIIP, IFL, et al.
• Guest Large Page Support. z/VM 6.4 now includes support for the Enhanced Dynamic Address Translation (DAT), allowing a guest machine to exploit large (1 MB) pages.  Larger page sizes decrease the amount of guest memory needed for DAT tables, therefore decreasing the overhead required to perform address translation.  In all cases, guest memory is mapped into 4 KB pages at the host level.

From a Linux environment viewpoint, z/VM V6.4 is a supported environment using IBM Dynamic Partition Manager for Linux-only systems with SCSI storage.  This simplifies system administration tasks for a more positive experience by those with limited System z Mainframe administration skills.  IBM Wave Version 1 Release 2 is now included in z/VM V6.4 as a priced feature, simplifying the task of administering a z/VM environment.  Using Dynamic Partition Manager, an inexperienced z/VM technician can create a z/VM partition in ~10 Minutes!

Supporting today’s agile application development and hybrid cloud implementations, z/VM and LinuxONE virtual servers can be natively managed using OpenStack open cloud architecture-based interfaces IBM OpenStack for z Systems.  OpenStack is an Infrastructure as-a Service (IaaS) cloud computing open source project, managed by the OpenStack Foundation.  With the adoption of OpenStack as part of the IBM cloud strategy, z/VM drivers provide OpenStack enablement for z/VM virtual machines running Linux on z Systems and LinuxONE.  Open standards such as OpenStack enable enterprises to be more agile, resolving potential issues such as vendor lock-in, technical expert recruitment, long application development cycles and security challenges.

The next evolution of z/VM cloud enablement technology is the OpenStack Liberty based Cloud Management Appliance (CMA), available for z/VM 6.3 and 6.4.  z/VM installations wanting to deploy cloud based solutions beyond Cloud Manager with OpenStack for z Systems, should utilize the cloud enablement support provided by the z/VM OpenStack Liberty based CMA.  This OpenStack Liberty based Cloud Management Appliance (CMA) replaces the IBM Cloud Manager with OpenStack for System z solution, withdrawn from marketing in June 2016.

The z/VM hypervisor extends the capabilities of z Systems and LinuxONE environments from the standpoint of sharing hardware assets, virtualization facilities and communication resources.  In conjunction with IBM Wave, z/VM makes it easier to derive maximum value from largescale virtual server hosting on z Systems and LinuxONE.  These benefits includes software and personnel savings, operational efficiency, power savings and optimal qualities of service.  The z/VM virtualization technology is designed to enable organizations to run hundreds to thousands of Linux servers on a single System z Mainframe footprint, alongside other System z Operating Systems, such as z/OS, z/VSE, or as a large-scale enterprise LinuxONE server solution.

Advanced virtualization features like multisystem virtualization and live guest relocation with z Systems, LinuxONE, z/VM, and Linux on z Systems or LinuxONE help to provide an efficient infrastructure for deploying private clouds to support workloads that scale both horizontally and vertically at a low total cost of ownership.

Although some might consider z/OS to be the flagship IBM system z Mainframe Operating System, arguably z/VM is the industry standard for optimal resource virtualization for numerous Operating System deployments.