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**** The Hebrew University of Jerusalem ****
**** Computation Center ****
News Bulletin #19
25-June-1991
Today's topics:
- New tape subsystem installed.
o New tape subsystem: Starting from today a new tape subsystem is
installed and can be used on both VAXes. The old system continues
to exist for a while until the new system will be proved reliable.
You can use at present both systems although it is highly
recommended that you switch to the new one as soon as you can.
The main advantages of the new system is that it allows tapes
access both from batch and interactive jobs (except from TK50/70
tapes which must be still used in batch mode - see explanation
bellow); it also allows simultanous access to more than one tape so
you can copy directly from one tape to another. The new system
consists of a single command called TREQUEST which is used instead
of the commands TAPE, MOUNT and INITIALIZE. It does not replace the
DISMOUNT command which you MUST issue when you finish working with
the tape(s).
When you want to mount a tape issue the command TREQUEST whose
format is:
$ TREQUEST/VSN=vsn/LABEL=tape-label [logical-name]
If you omit the logical name then TAPE is used. This command
instructs the operators to mount your tape. After the tape is
mounted you get a message on what drive it is positioned and the
logical name you specified (TAPE if not specified) is equated to the
drive name. This way you can use TREQUEST in command procedures and
batch jobs in which you don't know in advance which drive will be
used.
The command contains other optional qualifiers. Their
desciption and examples are given bellow. Note that the command
HELP TREQUEST gives you a detailed explanation of this command.
/VSN=tape-number - Lists the tape's external number as given to you
by the librariran. This parameter is necessary as it identifies the
tape to the operators.
/LABEL=tape's-label - Gives the tape label which you think is
recorded on the tape. The tape will be mounted correctly even if
the label recorded on it is different and you are notified for the
correct label. When a tape is to be initialized the label you
specify here is written on the new tape. when the tape is to be
handled as a non-labeled one (like ones with no files structure)
specify /NOLABEL to instruct the MOUNT process to ignore any labels.
/FOREIGN - (default is not /FOREIGN): Requests the tape to be
mounted a foreign one. Must be used when the tape is to be handled
by BACKUP.
/BLOCK_SIZE=number - Specifies the tape's block size. Used only
when the tape is to be handled as unlabeled (i.e. when the tape
contains no standard ANSI headers and the files on it are in fixed
record format).
If you do not specify this qualifier the tape is handled as one with
variable length blocks suitable for BACKUP operations and COPY with
standard ANSI headers.
/RECORD_SIZE=number - Specifies the tape's record size. Used only
when the tape is to be handled as unlabeled. (i.e. when the tape
contains no standard ANSI headers and the fiels on it are in fixed
record format). When you specify this parameter you must also
specify the block size; the block size must be an integral multiple
of the record size.
/CACHE - Sepcifies that the drive's internal cache is to be used.
Valid only on TA90 tape drives.
/INIT - Requests the tape to be initialized. Note that the contents
of the tape are lost when this is done. When you request a tape to
be initialized you must also specify the tape's density to use, and
you must add the /WRITE qualifier.
Note: The initialize procedure done by this command only rewrites
the first block of the tape. It does not physically erase the
contents of the entire tape.
/DENSITY=800 or 1600 or 6250 - Sepcifies the density to initialize
the tape to. You must supply this parameter if you specify the
/INITIALIZE qualifier; otherwise it is ignored.
/WRITE - Instructs the operator to attach a write ring to the tape.
If not specified the default is to mount the tape for read only
access. You must add this qualifier when you want the tape to be
initialized.
/OVERIDE - This qualifier overides all checks (expiration, owner,
etc.). Should be used only when the normal TREQUEST command fails.
This qualifier should not be used when the tape label is unknown as
TREQUEST finds the correct label and uses it.
Examples:
Mount a tape for reading files from it. The tape was written on VMS
or PDP system with the COPY command and has files structure on it:
$ TREQUEST/VSN=TK0005/LABEL=FILES
$ COPY TAPE:TEST.FILE SYS$LOGIN:*.*
$ DISMOUNT TAPE:
Mount a tape for backup use. we want to initialize the tape at high
density:
$ TREQUEST/INIT/DENSITY=6250/WRITE/VSN=PR0001 -
/LABEL=BACKUP/FOREIGN
$ BACKUP/LABEL=BACKUP/LOG SYS$LOGIN:LOGIN.COM TAPE:LOGIN.COM
$ SET MAGTAPE/REWIND TAPE:
$ BACKUP/LIST TAPE:
$ DISMOUNT TAPE:
We have a file structured tape and we want to copy the entire tape
to another tape:
$ TREQUEST/VSN=PR0001/LABEL=OLD TAPE1
$ TREQUEST/VSN=PR0002/LABEL=NEW/WRITE/INIT/DENS=6250 TAPE2
$ COPY/LOG TAPE1:*.* TAPE2:
$ DISMOUNT TAPE1
$ DISMOUNT TAPE2
We have a tape which was written on an IBM system in fixed records
of 80 bytes, 100 records in a block (thus a block length of 8000
bytes). There are two files on it; however, since the tape is not
file structured there are no names for them, nor there is a label:
$ TREQUEST/VSN=ST0005/NOLABEL/BLOCK=8000/RECORD=80
$ COPY/LOG TAPE: FIRST.FILE
$ COPY/LOG TAPE: SECOND.FILE
$ DISMOUNT TAPE
TK50 and TK70 note: These tapes MUST be read using batch. In order
to process them prepare a command procedure with the relevant
TREQUEST command and submit it to the TK70 queue ONLY; to submit to
the TK70 queue use the command SUBMIT/QUE=TK70.
__Yehavi:
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