device allocated on another node in cluster?
Lee Schultz
I have looked through the manuals, I even called software support in
Colorado, but have not come up with a solution that I like or desire.
System configuration: VMS v5.3-1, VAXcluster, HSC50 w/TA81.
Problem:
Person A on one node of the cluster allocates the TA81 for use. Person B on
a different node in the cluster wishes to use the TA81.
Both users are running command procedures.
Question:
How does Person B determine that the TA81 is really allocated?
The command SHOW DEVICE shows that the TA81 is allocated. Using the /FULL
qualifier shows the node on which it is allocated!
I have tried using the F$GETDVI lexical. It returns the correct information
if both users are on the same node, but the TA81 is *always* available for use
(i.e. not allocated) if you are on a different node.
I know I could write another command procedure that uses SYSMAN, as suggested
by Colorado, to determine the status of the TA81 on each node and updating
some file to know if the TA81 is allocated, but that seems like using a bucket
of water to put out a match.
I also know I can use ON WARNING THEN do what I want, but this is NOT what I
want/desire/need. (If the procedure runs for 2-3 hours, doing many tasks, but
I only need the TA81 for 10-15 minutes at the end of the procedure, I do not
want to allocate the TA81 at the start).
Am I missing something obvious?
*****************************************************************************
* Lee Schultz Assistant Director, Academic Computing Services *
* College of Wooster (216) 263 - 2242 *
* Wooster, Ohio 44691 USA SCHULTZ @ WOOSTER.bitnet *
*****************************************************************************
Jerry Leichter
I have looked through the manuals, I even called software support in
Colorado, but have not come up with a solution that I like or desire.
System configuration: VMS v5.3-1, VAXcluster, HSC50 w/TA81.
Problem:
Person A on one node of the cluster allocates the TA81 for use. Person
B on a different node in the cluster wishes to use the TA81.
Both users are running command procedures.
Question:
How does Person B determine that the TA81 is really allocated?
The command SHOW DEVICE shows that the TA81 is allocated. Using the
/FULL qualifier shows the node on which it is allocated!
I have tried using the F$GETDVI lexical. It returns the correct
information if both users are on the same node, but the TA81 is
*always* available for use (i.e. not allocated) if you are on a
different node.
I know I could write another command procedure that uses SYSMAN, as
suggested by Colorado, to determine the status of the TA81 on each
node and updating some file to know if the TA81 is allocated, but that
seems like using a bucket of water to put out a match.
I also know I can use ON WARNING THEN do what I want, but this is NOT
what I want/desire/need. (If the procedure runs for 2-3 hours, doing
many tasks, but I only need the TA81 for 10-15 minutes at the end of
the procedure, I do not want to allocate the TA81 at the start).
Am I missing something obvious?
No, I'm afraid not. VMS provides no program interface that allows you to
determine the status of a device on another node. $GETDVI, whihhc F$GETDVI
relies on, looks only at the local node's I/O database, which does not con-
tain detailed information (such as mount status) concerning other cluster
nodes.
SHOW DEVICE uses internal interfaces, and roots through various data struc-
tures, in order to get you this details information.
I'm not sure exactly what it is you are trying to accomplish; your comment
about only wanting the tape for 10-15 minutes of a 2-3 hour task only makes
things even more confusing. At the point where you need the tape, why not
simply try to allocate it? If you succeed, great; if not, wait a while and
try again. Even if you could test for the tape's availability, testing an
hour before you try to allocate it accomplishes nothing - the tape could
easily be busy by the time you need it.
So, what am *I* missing?
In any case, while I hate to suggest it, doing a SHOW DEVICE to a file and
extracting the information is about the only way to get the remote allocation
information.
-- Jerry