April 1, 1981 xiv Operating Systems in a Virtual Machine
Section 1. General Considerations
TheVirtual Machine Facility/310 (VM/370) provides an easy, convenient
way to use a single terminal to run other operating systems, such asDOS/VS, OS/VS1, or 05/VS2. with VM/310, system programmers can test a
new applicaticn program with an operating system, or they can develop
and test new operating system releases. They can do this work on any
shift, and they can do it isolated from any work that is running
concurrently elsewhere in the system. This isolation is done by the use
of a virtual machine.
A virtual machine is a functional equivalent of anIBM System/310 computing system. Each virtual machine has the functional equivalent of
a real processor, main and auxiliary storage, andI/O devices. Because VM/310 only simulates these functions, this simulated machine is
referred to as a"virtual" machine. V8/310 manages the functions of a
realIBM System/310 in such a way that virtual machines are available to
multiple concurrent users.
Before running any operating system in a virtual machine, an
installation shouldconsider: • How can application programs operate efficiently in a virtual
machine?• How it can reduce a virtual machine's I/O operations? • Which services are available for performance and communication for
bothVM/310 and a virtual machine? • What special considerations are there for multiprogramming operating
systems underVM/310, such as DOS/VS or OS/VS? • What operating system functions and devices does VM/310 support and
not support?• How to genera te a n opera ting system under VM/310? • How can virtual machines access the V8/310 system?
In answering these questions, this publication assumes that readers
have a basic understanding ofV8/310 concepts and functions as described
in the
understanding of whatever operating system they are running underVM/370. What virtual machine resources and operating systems can be used
underVM/370? VIRTUAL MACHINE RESOURCES Virtual machine resources are either shared among users or allocated to
users alternately for a specified time period. The resources to be
allocatedto any particular virtual machine are specified in the V8/310 directory entries for that virtual machine. The directory entries for
all virtual machinesmake up the V8/310 directory file that is usually Section 1. General Considerations 1
The
way to use a single terminal to run other operating systems, such as
new applicaticn program with an operating system, or they can develop
and test new operating system releases. They can do this work on any
shift, and they can do it isolated from any work that is running
concurrently elsewhere in the system. This isolation is done by the use
of a virtual machine.
A virtual machine is a functional equivalent of an
a real processor, main and auxiliary storage, and
referred to as a
real
multiple concurrent users.
Before running any operating system in a virtual machine, an
installation should
machine?
both
systems under
not support?
In answering these questions, this publication assumes that readers
have a basic understanding of
in the
understanding of whatever operating system they are running under
under
users alternately for a specified time period. The resources to be
allocated
all virtual machines
