Control Data Corporation CYBER 170 Series Operator's Manual page 70

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mounted, mount the tape on an available unit
(ensuring that track type and write ring status are
correct),read the unit, and enter this command.
The system equates the VSN entered by you with
that specified by the job and assigns the tape
automatically upon demand.
If the tape mounted on the tape unit defined by
EST ordinal xx is a labeled tape, has already had a
VSN assigned by console com mand, or has not yet
been checked for a label by MAGNET, this
command is ignored. The message
ILLEGAL ENTRY.
appears on the left console screen. To change a
VSN previously assigned by this command, clear
the first VSN by ente~ing
VSN,xx.
xx EST ordinal of the tape unit.
The command
VSN,xx,vsn.
vsn New VSN.
can then be entered. (The preceding message and
procedure for changing a VSN are also applicable
to the VSN,xx,. command.)
If a job specifies a VSN in the request for a
labeled tape, assignment . occurs automatically,
without your intervention, unless the correct tape
is not mounted. In this case, an entry is formed in
the resource mounting preview (E,P.) display
which describes the tape to be mounted. When
the tape is mounted and the tape unit made ready,
assignment occurs automatically without
additional intervention by you. For multireel
files, automatic tape assignment occurs only if
the tape units on which the tapes are mounted are
similar and on the same channeI(s}. That is, if the
first reel of the file is on a 669 tape unit on
channels 13 and 33, all subsequent reels must be
on a 669 unit on channels 13 and 33. When
assigning tapes, models 679-2, -3, and -4 drives
(800/1600 cpO are similar. Also models 679-5, -6,
and -7 drives (1600/6250 cpO are similar.
If two or more unassigned tapes having identical
VSNs are mounted on units of the same track
type, the flashing message
REQUEST,eq, vsn
appears on the B display. The eq field is either
the device type MT or the density requirement
HD, PE, or GE; vsn is the VSN required.
You must assign one of the tapes using the
ASSIGN command. If the duplicate VSNs are
SCRA TCH, the resource executive routine RESEX
assigns one automatically
I
NOTE
I
It is
not possible to specify a VSN of
SCRATCH with this command since
only six characters may be used to
define a VSN. To define a scratch
tape (used to satisfy scratch VSN
requests), refer to the description of
. the SCRATCH,xx. command.
SCRA TCH,xx.
Declares the tape mounted on an unassigned
magnetic tape unit, defined by EST ordinal xx, to
be a scratch tape. This command enables a tape
to be available to satisfy scratch VSN requests
and still be assigned by its original VSN. Thus, the
VSN defined on the tape (in VOL1 label) is not
redefined as scratch although the VSN will appear
as SCRATCH on the tape status (E,T.) display.
Scratch status is retained for only one job
assignment. This allows a tape to be used for
scratch purposes on a temporary basis. For
example, a job requests a tape mounted on the
tape unit defined in this command by specifying
the current VSN for that tape in the request. The
tape is then assigned to the job as a scratch tape
(the original VSN is retained and not made
scratch). When that job releases the tape,
SCRA TCH status is cleared, and unless this
command is entered again, that tape would not be
assigned as a scratch tape in future requests. To
determine if SCRATCH status is in effect for a
tape, monitor the tape status (E, T.) display.
VSN,xx,.
Declares the tape mounted on an unassigned
magnetic tape unit, defined by EST ordinal xx, to
be a scratch tape. This command is similar in
function to the SCRATCH,xx. command in that it
enables a tape to be available to satisfy scratch
VSN requests. However, if the tape is labeled and
a write function is performed, the VSN specified
in the VOL1 label· will be rewritten as a scratch
VSN, destroying the original VSN and making the
tape available for future scratch VSN requests.
The VSN also appears as SCRATCH on the tape
status (E,T.) display. Refer to the VSN,xx,aaaaaa.
command for a discussion of the ILLEGAL ENTRY
message which is also applicable to VSN,xx,.
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