(3) OptiJn ECMODE allows the virtual machine to use the complete set of virtlal System/370 control reqisters and the dynamic address
translation feature of the System/370. (4) The address of the virtual machine console is 01F, and your system corresponds with the terminal as if it were a .... ,... .. I:" I"")"' ... n ..)":;I:J,..)":;IV. (5) The virtual unit record devices (reader, punch, and printert are to
be and their addresses, as far as the virtual machine is
concerned, are OOC, OOD, and OOE, respectively.
(6) In this configuration, a 50 cylinder read/write minidisk with a
virtlal address of 130 is located on cylinders 50 through 99 of a
real 2314 volume labeled VSDISK1. Similarly, a 20 cylinder read/write minidisk with a virtual address of 151 is located on
cylinders 1 through 20 of a real 3330 volume labeled VDISK2. The
last entry provides a to a sharaole eMS system volume so the
user can use such CMS functions as the CMS editor or the EXEC processor. The LINK entry makes the virtual disk at virtual
address 440 available to your virtual machine in read-only mode at virtual address 190. NQi§§: 1. The cead password entry (RR) on
with the proper password can
read-only mode.
the LINK command means that anyone
share the use of the minidisk in
2. The access mode (WR) on the LINK command means that you can write to the disk as long as no one else has a link to it; if someJne else links to it before you log on, you still have read-only access.
3. detailed information on directory "Directory Control Statements" in the entries, see the section Some ievices such as unit record devices (readers, printers, and
punches) are usually defined as being spoolei; in this way, a few real
unit record devices can support a larqe number of virtual unit record
devices. Other devices such as magnetic tapes require a one-to-one virtual to
real This means that for its period of use, the device
must be dedicated to one virtual machine. For this reason, these devices are not permanently assigned; (that is, they are not defined in
the user's VM/370 directory entry). They are temporarily attached to a
user's victual machine as needed. VIRTUAL DISKS ITnder VM/370, a single real direct access storage device (DASD) can be
manaqej as if it were made up of a number of virtual disks (minidisks). Virtual disks, to VM/370, are extents on real DASD. To the virtual
machine, they functional equivalents of real disks. They can range
from 1 cylinder to all of the cylinders available on a real volume. Virtual disks can be permanently or temporarily defined for your virtual
mach ine.
section 3. CP Command Usage 15
PERMANENT VIRTUAL DISKS Permanent virtual disks are defined in your VM/370 directory. They can be your own personal disks which you mayor may not wish to have other
users or, they may be disks, owned by one user, but qenerally shared in read-only mode by any user on the system. Virtual
disks, definea in your directory, are made available to you when you log
on to the system. VIRTUAL DISKS If during a terminal session you require additional disk space, you can
define a temporary minidisk via the CP DEFINE command:
define t2319 as 133 cyl 15
In the previous example, a virtual 2319 disk compr1s1ng 15 cylinders is al13cated to vour virtual machine at virtual address 133. You can then
notify your operating system of the additional storage space using the
appropriate control statements or commands. the previous structure or use of this temporary disk space is
unknown, must format it to conform to the operating system you are
usinq. For :::r.JS,. use the CMS FORMAT command. For as, DOS, or VSAM applicltions, use the IBCDASDI program. When you have no further need for temporary disk space, you can
release the space to the system by issuing the command: deta:::h 133
If you 10 not release it during your terminal session, it is
automatically released to the system when you log off. NQtg: When temporary disk space is released to the system, it is not alltomat ically cleared.. Another user, requesting temporary disk space
and re:::eivinq all or part of your former disk area, can access any data
that yocr had left there. To preserve security, you should clear all temoorarv disk space before detaching it or logging off. SHARING VIRTUAL DISKS You can liso gain temporary access to someone else's permanent virtual disk during terminal session. You must know the userid of the
disk's owner, as well as its virtual address in his system. If the
owner is :::ontrolling the access to his disk, you have to obtain the read
or write password. You can then issue the command: r ,
link to smith 330 as 134 rr Irpasswdl L J
The virtual disk at address 330 in user SMITH's configuration is made
available to your virtual machine at address 134. You have read-only
access even if SMITH has the disk in write status. 16 V,/370 CP Command peference for General Users
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