Configurations (other) Other Considerations for Planning Your Configuration TWO-CHANNEL SWITCH If any I/O devices controlled by VM/370 for its exclusive use are
attached to control units with two-channel switches, the processor or
virtual machine controlling the other channel interface must vary the CP-owned devices offline. See the "VM/370 Using Channel Sw itching" section ea rlier in Part 1
for more information about using the two-channel switch. DEVICES USED ONLY BY AN OPERATING SYSTEM IN A VIRTUAL MACHINE AND NOT BY VM/3 7 0 Any input/output device that can be attached to the IBM System/370 can
be used by a virtual machine under VM/370 as long as there are: • No timing dependencies in the device or the program. • No dynamically modified channel programs except OS Indexed Sequential
Access Method (ISAM) or OS/VS Telecommunications Access Method (TCAM) Level 5. • None of the other restrictions outlined in "Appendix F: VM/370 Restrictions" are violated.
Dynamically modified channel programs (except those that have
input/output involving page zero) are permitted if run in a virtual=real
machine.
Input/output devices that are part of a virtual
configuration require real device equivalents, except for:
machine's • Unit record devices, which CP can simulate using spooling techniques. • Virtual 2311 Disk Storage Drives, which CP can map onto 2314 or 2319
disks. Up to two full 2311 units can be mapped onto a 2314 or 2319
disk in this manner.
Service Record File On 3031, 3032, and 3033 processors, each console station of the 3036 system console has a 7443 diskette attached to it, accessible when the
console station is in SRF mode. In the normal console configuration,
one of the processor's console stations is used as an operator's
console, and the other console station is used as a service console. It
is through the service console that SRF capability is provided. With the console in degraded configuration (i.e. one console station serves
as both operator and service console), there is no SRF capability.
Thus, it is recommended that the SRF address specified on the RIOGEN macro instruction at system generation be the address of the service
record file attached to the service console. 126 IBM VM/370 Planning and System Generation Guide

Configurations (Other) MULTIPLE SERVICE RECORD FILES In a 3033 attached processor system, there are two 3036 consoles. This
configuration has four service record file devices (one console per
station) . 3033 attached processor environments support multiple service record
file devices. For VM/370 systems operating on a 3033 AP, you should
specify multiple SRF devices at system generation. Code DEVTYPE=7443 in
the RDEVICE macro statement and CUTYPE=7443 in the RCTLUNIT macro
statement to generate support for the SRF devices; also code the ADDRESS=cuu operand in both macro statements. Identify the SRF device
addresses in the RIOGEN macro statement as SRF=(cuu,cuu, ••• ). The SRF addresses you specify in the RIOGEN macro statement should be the same
as the addresses of the SRF devices attached to the service support
consoles.
In 3033 multiprocessing environments with liD configured
asymmetrically to one processor, in order to access the SRF devices in
both 3036 consoles, a channel path must be available from the 110 processor to both SRF devices.
If an SRF device specified on the RIOGEN macro statement is found to
be inaccessible during initialization of the error recording cylinders,
an error message is sent to the system operator; processing continues
without the frames from that SRF device in place on the error recording
cylinders.
The RIOGEN macro statement produces an MNOTE warning message if you specify more than 32 SRF devices. Part 1. Planning for System Generation 127