It can be extremely useful to have a print queue which, rather than printing itself, forwards prints on to one of a number of other printers. Setting this up in PaperCut is a snap; create a new printer, mark it as a “virtual queue” within PaperCut, and choose which “physical” print queues it can release to!
A virtual queue isn’t intended to ever actually print anything, but rather send its jobs on towards other queues which are associated with real, physical printers. Such functionality is instrumental for features like Find Me Printing, where users all print to the one print queue, but then release at the printer closest to them.
However, if for some reason the PaperCut Print Provider suddenly stops working on your print server, any virtual queues cease to be virtual, and they will instantly start behaving like normal printers. If a virtual print queue is associated with an actual printer, this could be very bad news! Any subsequent prints which a user intends to release securely to a printer in one location would instead come straight out at whatever printer the virtual queue is associated with.
So how do we avoid this? Thankfully, it’s a very simple fix. Instead of creating a virtual queue that points at an actual, physical printer, we make one that points… well, nowhere at all. All prints that are unintentionally released to such a queue will vanish without a trace; in other words, no pages will come out, nobody will get their hands on a document they shouldn’t see, and no paper is unnecessarily wasted!
To achieve this within a Mac OS X printing environment, we recommend that your PaperCut virtual print queues be configured to print to file at “/dev/null”. This way, errant prints will be written out to a file stream which is not saved or stored. You can read more about that process over here.
For Windows, the process is a little different…
Setting Up a Windows Nul Port
The Windows Nul port (“Null” with a single letter ‘L’) is easily attached to a Windows print queue. Start by bringing up the Printer Properties for the print queue in question. Select the “Ports” tab, then click to “Add Port…”. Choose a “Local Port”, click on “New Port…”, and type in “nul” as the port name (minus the quotation marks). Click “OK”, then “Close”, then “Apply”, and you’re done!
Devices and Printers → Right-click Printer → Printer Properties → Ports → Add Port… → Local Port → New Port… → “nul” → OK → Close → Apply
If you are using LPR or Print Services for Unix, the Windows Nul port option may not work as expected.
When used on a virtual queue, the administrator should take into consideration the Failure Mode Settings. If set to Mode 1 or 2, the virtual queue will delete all print data sent to it during a failure preventing communication between the Application Server and the Print Provider on the virtual queue’s print server.