Large cups systems?

Seth Galitzer sgsax at ksu.edu
Mon Oct 15 12:06:56 PDT 2007


I'm using mostly PPDs, only a couple of raw queues due to deficiencies
in the PPDs  I'm not sure what you mean by "interface scripts".  Is this
some kind of lpr/printcap that's been shoved into cups, or something else?

All of my printers are connected via IPP/Socket, nothing direct via
serial.  I'm sharing the printers via samba to Windows and Mac OSX
clients, and to Linux clients via cups (the local machines refer to the
central cups server, rather than using local queues).

All of my printers, except two, are HP, so I'm using the hpijs filters
for all of them.  The other two are an Epson (for which I am using a raw
queue) and a Savin copier/printer (for which I am using a PPD from the
manufacturer).  I'm not using any classes, only printers.

The other major problem I have is that any print job that's more than
200KB or so will almost always block the queue.  The status will be
either "Network host 'foo' is busy; will retry in X seconds..." (X is
between 10 and 30 sec.) or "Connected to foo..."  It gets stuck in this
state until I clear out the queue and then restart the queue.  Sometimes
I have to restart the cups daemon.  In fact, I have one queue in this
state right now and the blocking print job was a little over 500KB.

CPU usage seems normal and I am usually able to stop the daemon without
having to manually kill processes, but sometimes I do.  lpstat still
responds at this time, it's just that jobs don't go through.

For hardware, I'm actually running the server in a VM.  The CPU is
identified as a 2.66MHz Xeon, I've allocated 2GB RAM, and am using the
e1000 NIC for all communication.  I'm not touching swap at all.

For software, I'm running cupsd and samba on a Linux (Gentoo) host.
Here are the relevant version numbers:
cups: 1.2.9
foomatic-db: 20060720
foomatic-db-engine: 3.0.20060720
foomatic-db-ppds: 20060720
foomatic-filters: 3.0.20060720
foomatic-filters-ppds: 20070501
hplip: 1.7.4a (includes hpijs 1.7.1)
linux kernel: 2.6.22

If that gives you any insight as to what might be my source of
instability, I'd appreciate any advice you could offer.

Thanks.
Seth

Bernd Krumböck wrote:
> At first I had to update the data.
> We migrated another lprng system to cups. This cluster processed 350000 jobs in the last two weeks. No PPD, only raw and interface scripts are used.
> 
>> I'd really like to know how you keep such a large configuration stable.  I've got roughly a dozen printers and a couple-hundred users and the whole system seems so flaky that if you sneeze too hard it falls apart.  I find I have to restart the cups service almost daily to keep things running.  I know my physical network is solid.  My configuration is pretty simple, I'm not doing anything fancy.
>>
> 
> We had problems with some earlier CUPS versions. But we hadn't any problem with stability since 1.2.11.
> I recommend you to use 1.2.12 or the latest 1.3.x.
> 
> Maybe your problem isn't the CUPS scheduler, maybe it's one of the filters or backends?
> How your printers are connected?
> Which filters you are using?
> 
> Please write down all symptoms before restarting:
> lpstat is working?
> scheduler use 99% CPU?
> Can you stop the scheduler?
> You need to use "kill -9"?
> ..
> 
>> So what's the secret?
> There is no secret. Only some analyses, a cool head and you sometimes need to be patient.
> 
>> More horesepower on my server?
> No. Only avoid swapping and a workload of 100%.
> 
>> Clustered servers?
> Clustering is always a good idea, but has nothing to do with CUPS stability if your hardware and os is working correct.  ;)
> 
>> More caffene?  I can live with limited driver capability, most of my users don't even notice, but the stability is a serious issue.  Anything, please, this is frustrating me to no end.
>>
> 
> We also had problems with stability (e.g. http://www.cups.org/str.php?L1439 and http://www.cups.org/str.php?L2311). So we searched in the CUPS forums and tried the last CUPS version. Without success.
> So we started to write down all symptoms. In the last consequence I learned some basics about CUPS source and gnu debugger.
> 
> I hope my story isn't frustrating you. If you have no idea how to debug the CUPS sources, then post all informations about your environment and all symptoms to this forum. Maybe someone can fix the problem.
> 
> CUPS is still (one of) the best printer scheduler we have ever seen, but it is not bug free.  ;)
> 
> regards!
> Bernd




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