Makes a foreign volume and the files or data it contains
available for processing by EXCHANGE. The EXCHANGE command MOUNT
enters the device into internal tables maintained by EXCHANGE.
Format
MOUNT device-name
MOUNT/VIRTUAL device-name file-name
1 – Parameters
device-name
Specifies the physical device name or logical name of the device
on which the volume is to be mounted. For MOUNT/VIRTUAL, the
device-name parameter supplies a name for the virtual device.
file-name
For MOUNT/VIRTUAL only, the file-name parameter gives the name of
the file containing the image of the foreign volume.
2 – Description
The EXCHANGE command MOUNT enters the description of the foreign
volume in internal tables maintained by EXCHANGE. This command is
different from the DCL command MOUNT, which enters the device in
tables maintained by the OpenVMS operating system.
A virtual volume must be explicitly mounted with the
MOUNT/VIRTUAL command.
If an EXCHANGE command is given on an unmounted foreign volume,
EXCHANGE attempts to execute an implied MOUNT/FOREIGN/WRITE-
/NODATACHECK on the device. This feature enables EXCHANGE to
operate in the single-command DCL mode.
If a MOUNT/FOREIGN (either implied or explicit) command is given
for a foreign device that has not been mounted on the OpenVMS
system, EXCHANGE issues the equivalent of the DCL command
MOUNT/FOREIGN and attempts to make the volume known to the
operating system. Any volume mounted in this way remains mounted
after EXCHANGE exits.
When EXCHANGE issues the MOUNT/FOREIGN command, the system checks
the following:
o That the device has not been allocated to another user
o That a volume is physically loaded on the specified device
o For magnetic tapes, the volume accessibility field of the VOL1
label
3 – Qualifiers
3.1 /DATA_CHECK
/DATA_CHECK[=(READ,WRITE)]
/NODATA_CHECK
Determines whether EXCHANGE performs a second operation after
every I/O operation to verify that the data was correctly
transferred. If you specify /DATA_CHECK=WRITE, after every
write operation EXCHANGE rereads the data that was just written
and compares it with the original data. If you specify /DATA_
CHECK=READ, EXCHANGE reads each block of data twice and verifies
that both read operations received identical data.
It is usually more efficient to use the /DATA_CHECK option on
the DCL command MOUNT than to use the option on the EXCHANGE
command MOUNT. If you mount a device with the DCL command
MOUNT/FOREIGN/DATA_CHECK, OpenVMS can use features in the
device hardware and device driver to perform the redundant I/O
operations.
The RX01 and RX02 diskette drives do not contain the necessary
features for the operating system to perform data checking. If
you use the DCL command MOUNT/DATA_CHECK with a diskette, the
system is unable to perform data checking (no warning message
is displayed). EXCHANGE is able to recognize, however, that a
diskette was mounted with the data checking option; in this case,
EXCHANGE performs the software data checking internally, even if
you have not specified an explicit MOUNT/DATA_CHECK command.
If you specify the /DATA_CHECK qualifier without an option, the
default is /DATA_CHECK=WRITE.
3.2 /FOREIGN
Indicates that the volume is not in the standard format used by
the OpenVMS operating system; that is, a magnetic tape volume
is not in the standard ANSI format, or a disk volume is not in
Files-11 format. The EXCHANGE command MOUNT mounts only foreign
volumes. The /FOREIGN qualifier is the default. You must use the
DCL command MOUNT to mount OpenVMS volumes.
The default protection applied to foreign volumes is RWLP (Read,
Write, Logical I/O, Physical I/O) for the system and owner. If
you mount a volume currently in Files-11 format with the /FOREIGN
qualifier, you must have the user privilege to override volume
protection (VOLPRO), or your UIC must match the UIC on the
volume.
3.3 /MESSAGE
/MESSAGE
/NOMESSAGE
Controls whether EXCHANGE displays a message indicating that the
volume was mounted. The default is determined by the /MESSAGE
qualifier specified with the EXCHANGE command when EXCHANGE was
invoked.
3.4 /VIRTUAL
Mounts a Files-11 file as a virtual device. When you specify
/VIRTUAL, the MOUNT command requires two parameters. The first
parameter is a device name assigned as the name of the virtual
device. The second parameter is the name of the Files-11 file
that is the image of a foreign volume.
3.5 /VOLUME_FORMAT
/VOLUME_FORMAT=option
Defines the physical format of the volume to be processed.
3.6 /WRITE
/WRITE
/NOWRITE
Controls whether the volume can be written. You can specify
/NOWRITE to protect files by providing read-only access.
Specifying /NOWRITE is equivalent to write-locking the device.
The default is /WRITE. If /WRITE is specified (either explicitly
or by default) and the volume itself is write-locked, EXCHANGE
displays a message to inform you that the volume is write-locked.
4 – Examples
1.EXCHANGE> MOUNT MT:
%EXCHANGE-I-MOUNTED, MATH06 mounted on _MTA0:
The command in this example requests that the magnetic tape
loaded on the device MTA0 be mounted as a foreign volume. The
tape label is displayed, since the tape has been previously
initialized as an ANSI-labeled tape with the label MATH06.
This tape cannot be accessed as a Files-11 tape; it should
be reinitialized as a DOS-11 tape during the current EXCHANGE
session.
2.EXCHANGE> MOUNT DMA1:
%EXCHANGE-I-WRITELOCK, volume is write-locked
%EXCHANGE-S-MOUNTED, volume DMA1: mounted
The command in this example mounts the foreign volume that is
loaded in the RK07 device DMA1, making the volume available
for subsequent EXCHANGE commands. EXCHANGE recognizes that the
volume itself is write-locked, and displays a message.