Directory Program
program involving these devices can result in a hung or busy
condition (caused by a conflict in real-to-virtual I/O processing
through the common VCUBLOK). Therefore, when defining devices, make sured 11 the devices are defined (and separated) within their
own control unit range and not shared with other devices.
DEDICATE OB8 OBO is a DEDICATE statement for a device at real address OBOe Its
virtual address is OB8. DEDICATE 250 "YPACK is a DEDICATE statement that defines, for this virtual machine,
virtual address 250 as the real device where DASD volume MYPACK is mounted. Sin("C? 'tbC?rC? is no C"0n't!"01 l!ni't 0!! r,:acll for console it should be noted that this restriction applies to any
system console such as the 3138, 3148, and 3158.
This restriction also applies to SPOOL statements and combinations
of DEDICATE and SPOOL statements.
3. When the real device is a 3330V, the action VM/310 takes in
processing the DEDICATE statement at logon time depends on the
combination of operands specified. Following are the allowable
combinations and the control program action for each:
DED cuu rdev
The real device must have the VIRTUAL feature (not SYSVIRT). The
real device will be dedicated to the virtual machine as virtual
device cuu, which is a 3330-1. All cylinder fault activity on the
rdev will be processed by VM/370, transparently to the virtual
machine.
DED cuu rdev 3330V The real device must again be a VIRTUAL 3330V. All cylinder faults
and unsolicited interrups received by V"/310 on the rdev will be
passed to the virtual machine.
DED cuu volser
When processing this statement, the control program will allocate
an available SYSVIRT 3330V and dedicate that real device to the
virtual machine as virtual device cuu. The "SS volume having volser
will be mounted on the real device, and the virtual device will be
a 3330-1. This form of DEDICATE is used to dedicate volumes to non-MSS operating systems, such as CMS, since the control program
chooses the real device address and no cylinder fault interrupts
are passed to the virtual machine.
DED cuu rdev volser
The difference between this example and the one immediately
preceding is that in this case the real device address is
preselected and must have the VIRTUAL feature. This format allows
the installation to control which real devices are dedicated to
virtual machines, rather than having the control program choose a
device address when the statement is processed.
212 IB" VK/370 Planning and System Guide

Directory Program
DED cuu rdev volser 3330V This format is the same as the preceding, except that the virtual
device becomes a 3330V, such that VM/370 does not intercept any
cylinder fault interrupts or the associated attention interrupts.
4. There are considerations that must be made when dedicating real 3330Vs to a virtual machine that also has a dedicated MSC port and
is running an OS/VS operating system with support. (See
"Appendix F: VM/370 Restrictions.")
5. When dedicating a real CTCA, the CTCA should be on a separate real
channel from all other virtual devices because of a possible lOCK-out problem.
The LINK control statement makes a device that belongs to another user
(userid) available to this virtual machine at logon time. If you want
to make one volume available to several virtual machines: • Define the volume for one of the virtual machines with an statement. • Define a link to that volume, with the LINK statement for all other
virtual machines that use the volume.
Then, if you later must move or change that volume, you need only update
the one statement, the LINK statements need not be updated. The
format of the LINK control statement is: r I Link userid ldev [cuu (mode]]
L
userid
ldev
cuu
mode
is the 1-to 8-character user identification of the user to be
linked tOe is the virtual device address of the device owned by userid to
be linked to (3 hexadecimal This is the virtual
device address, assigned by userid, of the disk you wish to
link to.
is the virtual device address for the virtual machine being
defined. "cuu" defaults to the same address as the linked-to
device (3-hexadecimal digits). If your virtual machine has
the option, any address up to X'FFF' is valid;
otherwise, any address up to X'SFF' is valid.
is the primary access mode requested for the device
(read-only, write, or multiple-write), and the alternate
access (read-only or write) desired, if any, as follows:
R specifies that read-only (R/O) access is requested. The
link is not given if any other user has the disk in
write status.
RR specifies that read-only access is requested, even if
another user has the disk in write status.
Part 2r Defining Your VM/370 System 213