IBM ^
z/VM
Module 1: Introduction
The basic concepts and fundamental
ideas of z/VM
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IBM ^
Trademarks
 IBM, DFSMS/VM,
 Java and all Java-based
Hipersockets, z/OS, zSeries,
trademarks are trademarks of
z/VM, GDPS, Parallel Sysplex
Sun Microsystems, Inc. in the
and Tivoli are trademarks of
United States, other countries,
International Business
or both.
Machines Corporation in the
United States, other countries,
 Other company, product or
or both.
service names may be
trademarks or service marks of
 Microsoft and Windows are
others.
trademarks of Microsoft
Corporation in the United
States, other countries, or both.
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Objectives
 What we should be able to do:

Describe z/VM is and its benefits as an operating system

Describe a virtual machine and what it does

Describe the differences between a first level guest and a second
level guest

Define what is meant by virtualization technology

List four hardware resources that z/VM “virtualizes”

Name three examples of Virtualization and describe each

List three advantages that can be obtained by using Virtual
Machines
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Objectives continued

Define the following, note their differences, and tell how each
is used:
 SAF
 IFL
 LPAR

Describe the three different types of operating environments
for z/VM

Describe the conditions that led to the development of
virtualization technology
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What is z/VM?
 An operating system (VM = virtual machine)
 A hypervisor, which refers to a system that virtualizes the
real hardware environment
 Runs on the zSeries architecture created by IBM
 Latest version is Version 4, Release 4
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z/VM as an Operating System
 A highly flexible test and production environment
 Has the ability to run multiple machine images and
architectures
 Can simplify the migration from one release to another
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z/VM as an Operating System (2)
 Running an operating system in a virtual machine should be the same
as running an operating system on a real processor
 Storage, processors, and I/O devices should behave in the same way
on a virtual machine as on a real one
 z/VM’s user interface is its Control Program (CP) commands
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General z/VM Environment
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What are Virtual Machines?
 z/VM uses real resources to create virtual machines that include
processors, memory, I/O devices, and networks
 Virtual machines run as if a guest system was running on the real
hardware
 Virtualization Technology creates an illusion that z/VM uses to
virtualize hardware components
 VM allows users to run multiple copies and different types of
operating systems on the same mainframe system
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Creating System Level
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z/VM – Virtualization Technology
 Can reduce system administration costs for:

Planning

Purchasing

Installing new hardware
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Processor Virtualization
 The central processor is the core for:
The
real machine
The
virtual machine
 Virtualization features:
Makes
the guest operating
system believe that it
has exclusive control of the
processors
Actually
the processors are being
shared among many
operating systems
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Memory Virtualization
 This diagram shows the
translation process.
 Several different levels of
translation are needed:
Machine
Physical
Virtual
memory
memory
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Storage Virtualization
 Physical Storage
Direct Access Storage Devices
(DASD) are the main storage
device
Minidisks
are the partitions of
the DASD storage device
These
are the physical storage
devices that can be virtualized
to obtain virtual storage devices
 Virtual Storage
Virtual disks are high speed
disks that perform and are
capable of the same operations
as the physical storage devices
If
you have a CP failure or
shutdown all virtual devices are
lost
Virtual
storage increase
performance and can
increase total size of
storage devices
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I/O Virtualization
 I/O devices that can be virtualized:

Ethernet NIC (network interface card)

Game port controller

Serial controller (COM)

Parallel controller (LPT)

Keyboard controller
 I/O to device that can be virtualized:

Video adapter

Mouse and keyboard

Console interface
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Examples of Virtualization-VTAPES
 Virtual tapes

You can define and use virtual tape drives as if they were real
tape drives

Like real tapes, virtual tapes can be:
–
–
–
–
–

Mounted
Written
Rewound
Read
Unloaded
When a virtual tape is no longer required, it can be scratched
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Three Advantages of Using VM
 Highly flexible environment
– Multiple machine images
– Many guest utilizing the same hardware
 Consolidates resources
– Cuts down on physical resources and space
– Condenses many operating systems into one server
 Increased performance
– Enhancement for z/VM 4.3 is its Timer Management
– Reduces bottlenecks and increases performance
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Important Building Blocks of z/VM
 SAF
– System Administration Facility
– Similar to the Virtual Image Facility (VIF), an earlier component
– Has additional tools that provide:
• Easy migration for your existing Linux distribution
• Configuration files
• Linux images
• Data to z/VM
– Comes standard with all z/VM 4.2, 4.3 and 4.4 packages
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Important Building Blocks z/VM
 IFL
– Integrated Facility for Linux
– Dedicated Linux engine for processing only Linux workloads
– Supports:
• Linux applications
• Linux operating systems
• Linux operating system in conjunction with z/VM
– IBM’s IFLs are managed by PR/SM as a logical partition with
dedicated CPUs
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Important Building Blocks z/VM
 Logical Partitions (LPARs)
– Provide the ability to share a single server among separate
operating system images
– Help create a secure computing environment
– Processors can be dedicated or shared
– Can have multiple LPARs per server (up to 15 LPARs in a
z900 server and up to 30 LPARs in a z990 server)
– Used in environments where separation of workloads is
required, but where the use of a single hardware platform is
desired
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Virtual versus Real
Environments
 Virtual: (z/VM)
 Can be functionally richer
than a real environment
Simulates hardware that does
not have to exist in the real
system, such as virtual tapes

Can share a single copy of an
application with many users

 Real: (LPAR)
 Has limitations depending on
the hardware
Hardware necessary to
accomplish your task can be
expensive

Supports only one
application for a single user

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Operating Environments
 Logical Partitions (LPAR)

Hardware partitioning that enables up to 30 "logical partitions“ in the
z/Architecture

Each LPAR runs a separate operating system

Each LPAR can run a different operating system
 Virtual Partitions (z/VM)

zSeries virtualization technology

Supports large numbers of Linux images and other operating systems

Provides management capabilities

Very flexible; great for server consolidation
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Running z/VM on an LPAR
 Logical partitions (LPARs) can over time reduce costs and
increase flexibility
 z/VM on LPARs gives users better security with more control
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How z/VM Fits with z/Architecture
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Changes and Growth of z/VM
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Versions and Releases
 Version changes:

Indicate a significant change in capabilities

May also change the software price
 Release changes:

Indicate that an incremental change has been implemented
 Point Release changes:

Indicate a service release or update
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z/VM Version 4 Release 3-Expanding Virtualization Technology
 Virtualization Technology exploitation
– Accounting of Virtual network resources
– I/O priority queueing
– Improved DASD and minidisk cache
 Connectivity Enhancements
– Multicast support for HiperSockets
– Simulation of a QDIO network adapter
 System Management Improvements
– Better utilization of large real storage
– RACF for z/VM as an optional, priced feature
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z/VM Version 4 Release 4 – Improves Virtualization Capabilities for
Linux on zSeries
 Virtualization Technology and Linux Enablement:
– Helps reduce overhead and may improve performance of virtual
machines on z990 servers
– Manages large numbers of virtual machines with high efficiency
 Network Virtualization Enhancements:
– Additional network-traffic configuration options using Virtual LANs
(VLANs) and Virtual Switching
– Extended HiperSockets support
 Technology Exploitation – Support for IBM z990:
– Improved logical-partitioning scalability with Logical Channel
SubSystems (LCSS)
– Improved capacity planning and I/O performance measurements
– Supports up to 30 logical partitions (LPARs)
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Key Concepts
 Virtual machines emulates hardware and allows multiple users
to use the same hardware components
 The importance of virtual machines:

Virtual machines (VM) run as they were running on the real
processor

Can use hardware that does not have to exist in the real system
by simulation and virtualization

Virtual Machines can share a single copy of an application
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Key Concepts continued
 What is Virtualization Technology:

With virtualization technology, z/VM users can easily create many
virtual machines consisting of:
–
–
–
–

Virtualized processors
Virtualized memory
Virtualized storage
Virtualized I/O resources
These can reduce administration costs and the overhead of
planning, purchasing, and installing new hardware to support new
workloads.
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Key Concepts continued
 The different types of environments:

Logical Partitions (LPARs)
– Each of which runs a separate operating system

Virtual Partitions (z/VM)
– Support for large numbers of Linux images and other
operating systems

Running z/VM on a LPAR
– z/VM on LPARs gives users better security with more control
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Conclusion
While z/VM has proven itself as an advanced technology, cost
effective tool for server consolidation for over 30 years, the advent of
Linux running on IBM mainframes has created a new awareness and
new demand for the power and flexibility of the IBM virtualization
operating system. z/VM provides not only the ability to share
hardware and software resources, it also gives the users maximum
flexibility to respond to today’s business challenges.
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Glossary
 Conversational Monitor System (CMS)- A component of z/VM that runs in a
virtual machine and provides both the interactive z/VM end-user interface
and the general z/VM application programming interface. CMS runs only
under the control of the z/VM Control Program (CP).
 Control Program (CP)- A component of z/VM that manages the resources of
a single computer so that multiple computing systems appear to exist. Each
apparent system, or virtual machine, is the functional equivalent of the real
computer, and CP simulates the real machine architecture in the virtual
machine.
 Direct Access Storage Device (DASD)- A mass storage medium in which the
data access time is effectively independent of the data location. Analogous
to the hard drive in a personal computer system.
 HiperSockets- A hardware channel that provides high-speed TCP/IP
communication between logical partitions (LPARs) on the same IBM zSeries
server. It uses an adaptation of the queued direct I/O (QDIO) architecture.
 Hypervisor- has the ability to present virtual images of hardware control using
Control Program (CP) commands.
 Integrated Facility for Linux (IFL)- a dedicated processor that handles Linuxonly workloads
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Glossary continued
 Logical PARtition (LPAR)- A subset of the processor hardware that is defined
to support the operation of a system control program (operating system).
 Minidisks- a logical subdivision of a direct access storage device.
 OS/390- an operating system on the S/390 architecture.
 Queued Direct I/O (QDIO)- A hardware channel architecture for direct data
exchange with I/O devices, where both the I/O device and the program
running on the server refer to main storage directly through a set of data
queues. The QDIO architecture is used by Open Systems Adapter-Express
(OSA-Express), HiperSockets, and Fibre Channel Protocol (FCP) channels.
 Remote Access Control Facility (RACF)- a mainframe security product that
can run on z/VM.
 Real machine – refers to a single operating system that has exclusive usage
of the underlying hardware system. Personal computers operate as real
machines.
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Glossary continued
 Release- an incremental set of changes to a level of software.
 Restructured EXtended eXecutor (REXX)- a programming language that
uses English-language like statements.
 System 360- the first mainframe architecture, which was created to run
multiple discrete workloads.
 Transaction Processing Facility (TPF)- an operating system that provides real
time, high volume transaction processing capability.
 Version- a significant change in software product capability. May be
associated with an increase in software price.
 Virtualization- A technology that facilitates the creation of many virtual
machines, consisting of virtualized processors, communications, storage,
and I/O resources, on a single hardware system. The technology allows
virtual machines to use hardware components, but they are indirectly
accessed through virtualization.
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Glossary continued
 Virtual images- copies of hardware that reflect the underlying system
architecture.
 Virtual machine- (1) A virtual data processing system that appears to be at the
exclusive disposal of a particular user, but whose functions are accomplished
by sharing the resources of a real data processing system. (2) In z/VM, the
virtual processors, virtual storage, virtual devices, and virtual channel
subsystem that CP allocates to a single user. A virtual machine also includes
any expanded storage dedicated to it.
 VM/ESA- An earlier version of z/VM for 31-bit architecture systems.
 Virtual Storage Extended/Enterprise System Architecture (VSE/ESA) - an
operating system that runs on S/390 and 31-bit architecture-capable zSeries
systems. Supports small and medium business applications.
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Glossary continued
 z/Architecture- An IBM mainframe computer and operating system
architecture that includes most of the facilities of S/390 and provides
significant extensions such as 64-bit registers and addressing.
 z/OS- a mainframe operating system that supports both older COBOL-based
applications and newer internet and Java-enabled applications, providing a
comprehensive and diverse application execution environment. z/OS 1.4 is
available on the Marist z900 server.
 z/OS.e- a specially-priced version of z/OS that provides select z/OS functions
for the z800 and z890 processors.
 z/VM- an operating system that runs on zSeries mainframe servers. It takes
advantage of the 64-bit capabilities of z/Architecture.
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