The following is an example of ATTACH statements that can cause
operational conflict.
att 10f to jones as 20c att 20e to jones as 20d (10f is a real 3211) (20e is a real 3277 terminal)
In the above example, the virtual addresses of both the 3211 and
the graphic device indicate the use of the same channel and control
unit. By definition, the devices are virtual and therefore will share one common virtual control unit (VCUBLOK) in CP.
The real 3211 printer operates on a nonshared subchannel, and the
real 3270 device is designed for shared subchannel operations.
Both of these real devices are mapped to the saae VCUBLOK. Thus,
the subsequent processing of a channel program can result in a hung
or busy condition (caused by a conflict in virtual-to-real I/O control procedures).
Therefore, when defining devices, make sure the devices are defined
(and separated) within their own control unit range.
Note: This same type of virtual device addressing conflict can occur with the use of any command or process that alters virtual
address (es) in the user's VM/370 directory entry.
If a device containing ainidisks is mounted and readied axter VM/370 has been loaded onto the system, the systea operator must
attach the device to the system. Subsequent logon operations by
virtual machines can link to this disk if provided by their
directory entry. Users who had been previously logged on to VM/370 (who possess a directory entry for the minidisk) aust issue,
subsequent to the DASD attach operation by the system operator, the
LINK command for access to the device. 7. When multiple devices or a range of real devices are specified on
the ATTACH co •• and line and the syntax is correct, all real device
addresses on the command are processed regardless of whether errors
are encountered when attempting to attach these devices.
Therefore, if the following command was issued
attach 108-10F userl r
and real devices 101 and 10D were not ready and online, the
following devices vould be successfully attached 108,109 10B,10C, 10E,10F Informational messages inform the operator
vere successfully attached. Error messages
that are not successfully attached.
of those devices that
identify the devices
8. To avoid the repetitious attachment of many devices to a virtual
machine, it aight be to the user's advantage to have these devices
attached to his virtual machine via the DIRECTORY DEDICATE
statement. Thus, by fulfilling logon requirements, these devices
(if online) are automatically attached to the virtual machine.
Section 3. CP Commands 47

In the case of virtual DASD volumes associated with the 3850 Mass Storage System, the ATTACH command allows 3330V devices to be
attached to a virtual machine without requ1r1ng a volume to be mounted. This is necessary because staging of cylinder 0 on a
virtual volume is not accomplished until a MSC mount order is issued associating the ?irtual unit address with a volume serial.
Even if the mount order was issued prior to the ATTACH, the host
system may change the data staged on a virtual volume by issuing
another MSC mount order.
9. If R/O is specified with a range of addresses or with multiple
addresses, this operand apFlies only to DASD addresses. The R/O operand is ignored for all other device addresses specified on the
command line. 10. Do not attach virtual 3330 volumes (3330V) to the SYSTEft; 3330V cannot be used for minidisks, CP residence, paging, or spooling
activity. Messages are sent to the user, the operator who issued the command (if
different fro. the user), and the primary system operator (if different
from the operator who issued the command), notifying them that the
ATTACH was successful.
type raddr ATTACHED
raddr ••• ATTACHED
raddr-raddr ATTACHED
Depending upon the form used for the co •• and line, the appropriate message indicates to the user the real device or devices attached
to his virtual machine. If multiple addresses or a range of
addresses are specified, the device type is not displayed.
type raddr ATTACHED TO userid vaddr
type raddr ATTACHED TO SYSTEM volid
raddr ••• ATTACHED TO userid
raddr-raddr ATTACHED TO userid
Depending on the form used by the class B operator for command line
entry, the appropriate response indicates the real device(s) that
are attached to CP or a specified user's virtual machine (and, if
appropriate, the virtual address of the device). If multiple
addresses or a range of addresses are specified, the device type is
not displayed.
type raddr ATTACH TO SYSTEM volid BY userid
-- or --
type raddr ATTACH TO userid vaddr BY userid
is the response to the primary system operator (if he did not issue
the co.mand) indicating that the real device has been attached
either to the specified user's machine at virtual address vaddr or
to the CP system by the specified class Buser. 48 VM/370 operator's Guide