SAMPLE DIRECTORY ENTRIES Tbis topic shews some useful virtual machines that can be defined when
running oFerating systems in virtual machines. Sample directory entries
fer running specific operating systems under VM/370 are in the operating
system dependent sections in this publication.
The fcllowing directory entry represents a multiple-access TSC system
configured tc handle one to four concurrent remote terminals and one
lccal 3270. It has been given the VIRT=REAL option to improve response
time. USER TSOSYS PASSWORD 384K ACCOUNT ACCTNO BIN8 IPL 290 OPTION REALTIMER VIRT=REAL CONSOLE 01F 3215 SPOOL OOC 2540 R SPOOL OOD 2540 P SPOOL OOE 1403 DEDICATE 290 TSOSYS DEDICATE 291 TSOWRK SPECIAL 070 3270 SPECIAL 080 2702 IBM SPECIAL 081 2702 IBM SPECIAL 082 2702 IBM SPECIAL 083 2702 TELE The directcry entry for this virtual machine has the ECMODE and
REALTIMER oFtions, allowing its user to check a new CP nucleus before meving that nucleus to the production system. TESTSYS contains two minidisks, 350 and 351. These disks are exact copies of the real system residence and scratch volumes. They are formatted and allocated so that
the real system can spool and page on these disks. If a user needs
additional disks, link to them before loading the virtual system. USER TESTSYS PASSWORD 512K ACCOUNT ACCTNO BIN11 OPTION ECMODE REALTIMER CONSOLE 01F 3215 SPOOL C 2540 R SPOOL D 2540 P SPOOL E 1403 LINK VMSYS 190 190 RR MDISK 191 3330 161 10 UDI SKA iR RPASS WPASS MDISK 350 3330 1 15 SYSWRK WR RPASS WPASS MDISK 351 3330 16 20 SYSWRK WR RPASS WPASS Section 1. General Considerations 49

Summary Te run any eperating system in a virtual machine, an installation
should: • Design new and existing application programs to operate efficiently
in a paging environment; that is, have them use VM/370 paging instead
of DOS/VS or as/vs paging. • Reduce a virtual machine's I/O operations. • Use VM/370 services for performance and communication, such as the VM/310 virtual machine options and VMCF. When running specific multiprogramming operating systems under VM/370 (such as DOS/VS or OS/VS), an installation should consider how that
system interacts with VK/370 -- especially when that system has a page
wait or I/O wait. To interact with these VK/370 provides VM/VS handshaking for certain DOS/VS and VS1 systems, and the diagnose
interface fer virtual operating systems, such as DOS/VS and OS/VS. Other areas to consider when running multiprogramming operating
systems under VK/370 are spooling, channel whether
to use multiple or alternate consoles, and the states or conditions of
virtual devices (dedicated, shared, and spooled). VK/370 also supports alternate paths, multiple-access virtual
machines, eperating systems using reser7e/re1ease, and the ASP virtual machine. Installations can also alternate between operating
systems under VK/370. While difficult to predict, performance of any virtual machine may be
impreved by the choice of hardware, operating system, and VK/370 eptiens. VM/370 also provides the INDICATE and MONITOR commands to
track and measure both VK/370 and virtual machine performance. VM/370 can help considerably throughout the system generation
process. Its biggest advantage is allowing an installation to generate
a system under VK/370 without disturbing production activity.
To allow virtual machines to access the VK/370 system, the VK/370 system requires a file of directory entries that contains one entry for
each virtual machine. Each directory entry contains a number of
directory control statements that define the virtual machine's
ccnfiguratien and operational characteristics to VM/370. Some directory
statements have unique considerations when running an operating system
in a virtual machine. There is an AUTOLOG facility to automatically
initiate large producticn operating systems with many I/O devices under V!1/370. 50 IBM VM/370 Operating Systems in a Virtual Machine