Barry:
The behavior you mentioned has been a part of MPE since at least 1978 and
MPE II (which is as far back as I go on the HP3000). If there are two or
more printers in the same device class, the spool file at the head of the
queue for that class goes to the first free printer in the class. The
situation gets a little more complex when you have printers which "share"
queues.
Say you have two printers, LDEV 90 and LDEV 91, both in the same device
class "LOCALPR". If you specify LDEV 90, your print file will be placed
in a queue for LDEV 90. IF you specify LDEV 91, your print file will be
placed in a separate queue for LDEV 91. If you specify "LOCALPR", your
print file will be placed in a queue which is serviced by whichever of
LDEV 90 and LDEV 91 is available first. Thus, you have three queues for
the two printers.
A common configuration (at least for us) is to have each printer have its
own class name. Where a bank of printers are co-located, and the
printers are of the same model or characteristics, two or more printers
may be assigned to the same class. Below is an example.
LDEV ClassName
90 BLDG05A WESTLPR
91 BLDG05B WESTLPR
92 BLDG11
93 BLDG15A EASTLPR
94 BLDG15B EASTLPR LASER LASER1
95 BLDG15C EASTLPR LASER LASER2
96 BLDG15D EASTLPR
If you print to WESTLPR, your output could go to either LDEV 90 or 91.
If you print to BLDG11, your output can only go to LDEV 92.
If you print to EASTLPR, your output can go to any of LDEV's 93, 94, 95,
and 96, with two of the printers (LDEV's 94 and 95) being lasers and the
other two (LDEV's 93 and 96) being plain old line printers.
If you print to LASER, your output gos to either LDEV 94 or 95.
People in building 15 who MUST have their output print on a laser printer
use device class "LASER" (or if they need a special feature like
duplexing, the device class "LASER1"). Those that just want it printed
and don't care what kind of printer it is printed on can use device class
"EASTLPR".
When you have this many queues the interactions can become complex and
determining which file will print next is sometimes difficult. The rule
appears to be (going out to the end of a limb) that if there is a file to
print in one of the queues associated with a device that services
multiple queues, the oldest spoolfile is printed first.
Please note that if you have a configuration like:
LDEV Class
90 LPR1 LPR
91 LPR2 LPR
You can have five queues - you have queues for "LPR", "LPR1", "LPR2",
"90", and "91".
This can also come in handy if you need to run your printer "hot" (as the
Navy forces us to do when printing checks). If your programmers are "well
behaved" and always use the class name for the printer (such as "LPR1"),
you can stop spooling on the LDEV (90 in this instance), close the queue
for the LDEV (again, 90 in this instance), and print to the printer "hot"
(unspooled) while applications are able to continue spooling output to the
open device class "LPR1".
Please also note that you can have all the queues shut (so no-one can
create any new spoolfiles) and yet have the printers busy printing (MPE
will do this for you if you run out of spool space or disc space).
At the other extreme you can have all the queues open (so people can create
new spoolfiles), but all the printers unspooled so that nothing prints.
HP came up with a very flexible spooling system that while the command
syntax is sometimes a nightmare, is very powerfull and adaptable to
almost any need.
Hope this explaination helps.
John
--------------------------------------------------------------
John Korb email: [log in to unmask]
Innovative Software Solutions, Inc.
The thoughts, comments, and opinions expressed herein are mine
and do not reflect those of my employer(s), or anyone else.
|
