I have a large RHEL 5 system which has started to exhibit flaky printing behavior. It is running CUPS 1.3.7-30. All the printers are parallel devices with various network-to-parallel converter devices (Zonet, D-Link, TrendMicro). We've switched back and forth between HPJetDirect protocol at port 9100, and IPP protocol at port 631 (sometimes one seems to work better than the other).

I can't really make any sense of what triggers the problem, which is intermittent, but the symptom is that print requests will pass through the system normally (showing up both in the A-Shell OPR:SPOOL.LOG and in the CUPS print log as having printed without error, but there was no printout on the printer).

I like the CUPS browser-based utility, which makes it easy for non-UNIX gurus to monitor the printers and perform simple tasks like pausing a printer and moving requests to another queue, but the utility itself seems somewhat flaky too.

The question is: what are people using for printing these days. In the early days of CUPS, I tried to avoid it because of problems like this, but Red Hat only supports CUPS. (The official Red Hat Network support has long expired, so there is nothing stopping us from using CentOS repositories though, other than the trickiness of trying to switch from CUPS to something else, and the uncertainty of whether anything else would be superior.

Any suggestions/feedback appreciated.

For what it's worth, I can't think of anything of value that my customers or I have printed directly from Linux in a long time. Almost every report and document that we generate gets converted to a PDF or CSV file and is sent to the local PC for viewing or import, and then if desired, normal network printing. Some output is simply saved on the network for retrieval by non-Linux programs.

We had similar problems when we used CUPS and HPJetDirect devices. Sometimes replacing the HPJetDirect or disconnecting/reconnecting it fixed the problem. But no one has reported Linux printer problems in years, leading me to conclude that no one is printing via Linux (even though we still support a dozen or so Linux printers).

We have cups 1.4.2 and have not experienced any problems like you are describing. We have no network to parallel converters, but from personal experience i would suspect these over cups.

I would tend to blame the network/parallel converters as well, but the problems don't seem to move around with the physical converters. (For example, if PTR1 is working and PTR2 isn't, swapping the converters doesn't necessarily swap the problem.) Plus the fact that there are 3 or 4 different makes/versions of them in use, all seemingly (but maddeningly intermittently) having the same kinds of problems seems to suggest the common element, which is CUPS.

Question: which printing protocol are you using?
And which Linux distro?

We're running CentOS 5 with CUPS 1.3.7-30 without these problem. Also, using HP JetDirect on port 9100

red hat 6.1, using lpr . i know i have one of those converters at home and it has a mind of its own.