Technical data

Managing Storage Media
9.8 Mounting Tape Volume Sets
Once the tape file system receives the REPLY command, the system performs
checks on the continuation volume to ensure that the volume is the correct one. If
it is the correct volume with proper access codes, the system mounts the volume
and reissues pending read or write requests to the continuation volume. If the
volume fails any of these access checks, the system does not mount the volume
(or initialize and mount it in the case of a blank tape).
9.8.3 Modifying Magnetic Tape Characteristics
Use the DCL command SET MAGTAPE to define the default characteristics
associated with a specific tape device for subsequent file operations. The SET
MAGTAPE command is valid only for magnetic tape devices mounted with foreign
volumes.
Use the following format for the command:
SET MAGTAPE device-name
where:
device-name Specifies the name of the tape device for which the characteristics are
to be set. The device must not be currently allocated to any other user.
The following examples illustrate uses of the SET MAGTAPE command in
conjunction with the MOUNT command.
Examples
1.
$ MOUNT MUB1:/FOREIGN
$ SET MAGTAPE MUB1:/DENSITY=800
In this example, the MOUNT command mounts a foreign tape on the MUB1:
drive. The SET MAGTAPE command defines the density at 800 bits per inch
for writing to the magnetic tape. (The density is reset only if the tape has
never been written before.)
2.
$ MOUNT MUA0: USER_VOL
$ SET MAGTAPE MUA0:/SKIP=FILES:4
In this example, the MOUNT command mounts a tape called USER_VOL on
the MUA0: drive. The SET MAGTAPE command directs the I/O subsystem
to position the tape to skip four files.
On local SCSI tape drives, you can use the /FAST_SKIP=option qualifier to
skip by file mark or by record. See the OpenVMS DCL Dictionary for more
information.
3.
$ MOUNT MUA1:/FOREIGN
$ SET MAGTAPE/REWIND MUA1:
In this example, the MOUNT command mounts a foreign tape on the MUA1:
drive. The SET MAGTAPE command rewinds the volume.
9–56 Managing Storage Media