Page of GC20-1806-9 As Updated April 1, 1981 by TNL GN25-0834 [TO] SYSTEM specifies, along with vOlid, that the DASD made available to CP for accessing users'
paging and spooling functions.
device is to be
disks and/or for [AS] volid is the volume label of the volume on the raaar being attached.
This operand has the following meanings when used with the
various forms of the ATTACH command: When used to attach an available raddr to a userid and the
raddr is a 3330V, the MSS volume with the label volid is
mounted on the raddr during the attach. When used to attach an raddr to the system and the raddr is
not a 3330V, the volume label of the volume on raddr is
verified. When used to attach an available raddr to the system and the raddr is a 3330V, the MSS volume with the label volid
is mounted on the raddr during the attach. When used to attach an raddr to a userid and the raddr is
not a 3330V, the volid operand is 3330V specifies that the vaddr is to be treated as a 3330V. The VM/370 control program assumes the virtual machine contains MSS device support. Consequently, MSS cylinder fault support
is not invoked for the vaddr. VOLID volid VOLID is a required keyword and 'volid' is the volume label
for the 3330V being attached.
1. It is possible to attach a disk to "SYSTEM" and attach the same
disk to a user without first detaching the disk if the disk was not
accessed while it was attached to the system.
2. A 370x cannot be used by VM/370 as a 370x unless it has been loaded
by VM/370, DOS/VS or OS/VS with 270x EP program and VM/370 was
generated with it specified as a 2701, 2702, or 2703. The ATTACH
and DETACH commands reset the "loaded" status.
3. The ATTACH
unless all
command.
command should not be issued for a
emulator lines have been disabled 370x in
by the
PEP mode
DISABLE 4. If the device being attached is a 2305 then both the real device
address and the virtual device address must be specified as the
first exposure on the 2305 (that is, device address 0 or 8). When attaching or detaching a dedicated 2305 to a user, all eight
exposures are processed.
5. If the virtual machine to which the device is being attached has
the ECMODE option, any address up to X'FFF' is valid as 'vaddr';
otherwise, any address up to X'5FF' is valid.
6. The hexadecimal address of the virtual device (vaddr) that is
mapped to the real device must be selected with care so that
conflict and contention caused by control unit I/O interface
protocol is avoided. Omitting this parameter causes the assigning
of the raddr as a default. 46 t1 M .t':;li" , .. ;.I....J I v Operator's
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
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